General

-序盤ではミニオンの攻撃は大きなダメージを与える。もし敵にミニオン数のアドバンテージがあるなら一般的には殴りにいかないように

-敵をAAで攻撃したらミニオンの攻撃を受けることになる。しかしスキルでハラスをするとミニオンから攻撃を受けることはない。

-茂みに入るとミニオンのフォーカスを外すことができる。ワードがある場合には解除されない。それはブッシュがワードされているか確認できる方法でもある

-敵のジャングラーがどこにいるか不明な時は過剰に攻撃的に攻めることは避ける 

-買い物に戻る前にはレーンを出来る限り素早くプッシュする でなければミニオンファームをロストすることになる

-過剰に頻繁な意味のないリコールは時間のロスになる リコールする場合は何か目的となるアイテムを購入出来る時か本当に回復が必要なときにしよう

-レーン相手がリコールしたらなるべくこちらも買い物をする でないとアイテムで不利を負うことになる

-敵のアイテムに気を配ろう もしRivenが赤エリクサーを持っていたら決して戦いを挑まないことだ

-Lv差に常に注意する もし相手が2Lvで自分が1Lvだった場合 マッチアップによっては深刻な問題となる(殺される可能性がある) またこれはLv6でも顕著に現れる もし相手が自分より早くLv6になったらそれは危険だ

-もしレーンで負けているなら経験値だけ取って耐えよう そしてGankが来るまで決して1vs1を挑まないこと

-自分の浸かっているチャンピオンの強みを知りそれを利用すること
もしLeesinを浸かっているなら序盤でアドバンテージを取れる
もしtristanaを使っているなら序盤で何かプレイを起こす必要はない ただファームをして終盤で活躍すればいい

-もしチームが負けている場合、投げやりになって無闇に集団戦を起こそうとしないこと
それより相手がミスをおかすのを待とう

-ドラゴンやバロン、味方のデスを諦めることも時には必要である 
敵がドラゴンをとっていて自分一人だけいきていたりして何もできないと判断した場合は潔く諦めよう
捕まって殺され、更にタワーまで失われたりすればそれはもう取り返しがつかない

-ダイブやキルを狙えるならジャングラーに呼びかけよう
また相手のフラッシュが落ちているならそれを伝え、またワードの場所も一緒に教えよう

-2靴に直行するのはジャングラーが5靴を買うというような場合でない限り大きなアイテム負けにつながる

-もしフェイスチェック(茂みを歩いて確認すること)する必要がある時はタンクに伝えてやってもらうのがより安全

-レーンで負けるのは構わないことだ 1killと30csの差でレーン戦が終わってもそれは許容範囲だ
でもそれを逆転しようとしてアグレッシブになると多くの場合5killを献上することになる

-スキルのレベルを上げる時はCtrl+スキルのキーで上げることに慣れよう 


Jungle

-バフは湧いたら素早く狩ること でなければ相手がスチールする可能性がある

-バフ、ドラゴン、バロンの復活時間は5/6/7分

-ドラゴンなどへトドメをさすときはスキルとSmiteを同時に使う(スチール防止のため)

-もしGankに成功したら95%の場合、レーンをプッシュするのを手伝った方がいい それによって相手の経験値をロスさせることができる

-味方が死んでレーンを代わりに維持しないといけない時にはなるべくフリーズ(出来る限りミニオンを倒さないこと)しよう 既にミニオンがプッシュしている時は一気に全てプッシュしきろう

-一番多くのCCがあるレーンをGankしよう

-CCがなかったり相手が離脱手段を持つレーンをGankしてはならない 過剰にプッシュしているなどのことがない限り
例えばNidalee vs zedのレーンでNocturneでGankをしても時間を無駄にするだけだろう

-負けているレーンはほどほどまでに助けよう 例えば2killされたレーンをGankしてこちら側が逆転するように努力することは多くの場合努力に見合った成果は生まれない
それどころか返り討ちに合う可能性もあるだろう

-(特に序盤で)ダブルバフを持っている時は決して死んではならない
もしキルできそうでも自分が死ぬ可能性も高い時は我慢して引くべき

-チームが負けている時にカウンタージャングルをするのはとてもリスキーである

-敵のジャングラーの動きを見て動きを予測することを学ぼう 
一番プッシュしているレーンのブッシュに隠れて待ってカウンターgankができる

-もし強力なUltを持っているキャラならそれが上がるたびにGankしよう

-レーンに誰もいなくてタワーにミニオンが食われてる時はファームしにいこう
レーンのミニオンはジャングルミニオンよりも価値がある

-決して無意味なgankを強行するな もしGankができるレーンもカウンターGankもできないならジャングルを回ろう

-ミニオンがこちら側に大量にたまっているレーンへGankしない
レーナーが死ぬ可能性がある上にミニオンをロスする可能性もある



Top


-経験からマッチアップ(相手レーナーとどちらが殴り勝てるか等)の知識を蓄える必要がある

-カウンターであるからというだけの理由で不慣れなチャンピオンをピックしないこと

-序盤にTopは一番Gankが来やすい 最序盤ではプッシュしないようにしよう

-多くの人は完全にプッシュしきらないで中途半端な位置までプッシュする(タワーの目の前)というミスをおかしている
このような場合にはタワーの前の位置でミニオンをフリーズして相手にCSをロスさせよう

-レーンをフリーズする時 過度にプッシュされすぎないように気をつけよう
大量のミニオンと一緒にダイブされる可能性がある

-もしリコールしないといけなくて でもプッシュをすることもできなく かつこちら側にややプッシュされている時はリコールすれば戻ってきた時にタワーにミニオンがつくようになっている
(つまりCSをあまりロストしない)
 
-負けている場合にはタンキーなアイテムを買おう タンクビルドの方が集団戦で活躍できる

-もし敵が5人でドラゴンをとって間に合うことができない時はプッシュしてタワーを折ろう


Mid
-ハラスをする時はAAを交えて

-Lv6になる直前では相手より素早くプッシュして早くLv6になり 攻撃をしかけよう

-キルが取れる確証がない場合は無駄にTopやBotへ行かないこと

-相手がRoamしてもう間に合わない時はプッシュしてタワーを攻撃しよう


ADC

-味方ミニオンのヘルスを見て敵がLHを取る瞬間にハラスをしよう

-最初のウェーブをプッシュされると相手が早くLv2になって大きな不利になる

-トレード勝ちできるならある程度のCSを捨てて一気に攻撃しにいくのは有効だ

-敵のアイテムをチェックして戦いを仕掛けよう (BFソードがあるかないか等)

-もしこちらに回復手段があり相手にないなら積極的にトレードをしかける

-もし相手のサポートを一気にバーストで倒しきることができてADCに逃げスキルがある場合にはサポートにフォーカスして一気に溶かす方が賢い 例えばSona+Ezが相手ならSonaを最初に殺しきることができればそうする方がいい

-タワーが折れた後の中盤以降でもファームを続けること

-集団戦では通常は安全な位置から攻撃できる相手を攻撃した方がいい
(ただし状況による 純Tankを攻撃し続けても負けるだけでしょう)

-チームでタワーを攻めている時、タワーを攻撃するのはADCの仕事だが 敵に掴まる危険性が高い場合は攻撃してはならない

-チームが負けている時には防御アイテムを買ったら勝つ可能性はとても低くなる

Support

-最序盤ではAAは大きなダメージ源である 敵が安全圏から離れたりLHを撮ろうとしてる時にAAで攻撃しよう

-サポートのレーンでの一番の役割は存在感を出して相手にプレッシャーをかけることである

-ワードを欠かさず もしない場合はプッシュしないように

-Pinkワードを活用しよう ブッシュに置けばジャングラーが潜んでいるかのような威圧感を相手に与えられる
また実際に味方のジャングラーを潜ませてGankをすることもできる
特にレーンで負けているならPink Wardを置いてGankしてもらうのは大きな有効性を持つ

(↑これはS3に書かれたガイドなのでPinkWardが不可視だった時なので今はあまり有効ではないと思います
今はブッシュにPinkを置いてもすぐ壊されてしまうだけでしょう)

-リコールする必要がある時はADCがレーンをプッシュするのを手伝う

-中盤以降のサポートの一番の役割は視界を制御すること

-もしチームが負けているなら味方のジャングルをワーディングしてさらに敵のワードを可能な限り壊して相手を捕まえることを狙うのが有効である

-集団戦では無闇にスキルを乱打しないこと
CCはADCを暗殺しにくる敵のDPSに使うこと


(ところどころ直訳もあり意味不明な訳もあったと思います)

(原文)

General tips

  • minions hurt, especially early level. Almost never go for a fight if the enemy got creep advantage or you lose the fight due to creep damage

  • whenever you attack someone with basic attacks, minions will start attacking you. Keep that in mind when trading. However, most spells won't trigger minion aggro so you can harass with spells without having to worry about creep damage

  • bushes remove minion aggro (unless it is warded - that's also a way of checking if a bush is warded or not)

  • don't be overly aggressive if you don't know where the enemy jungler is and you can't handle 1vs2

  • always try to push the lane before you go shop so you miss less xp

  • that said, dont waste your time by going back too often. I often see people basing for no real reason. Try to only base when you can shop something or you need to heal

  • most of the time you want to shop at the same time when the enemy laner goes shopping or you are at an item disadvantage

  • move to your lane as fast as possible after shopping. You can already start running and buying the moment you spawn in your base to get back a few seconds faster to lose less time

  • beware the enemy items. If you are vs. a Riven top with a red pot, be careful and don't fight him her early

  • watch levels: If you are still lvl 1 and the enemy hits lvl 2 before you, this can be a big problem in certain matchups. This is also true if the enemy laner hits 6 before you and he might all-in you

  • if you are losing a lane, try to stay at least in range of xp and don't go for 1vs1 anymore unless you have your jungler (and they dont have theirs)

  • know the strenghts/weaknesses of each champ and especially the one you are playing. If you play Lee Sin, you are strong early game so use this to your advantage. If you play something like Tristana, you don't need to make plays early and just play it safe and farm up

  • when your team is behind, don't force fights out of despair. Instead, try to stall and wait for them to make mistakes

  • it's okay to give dragons/towers or even kills up. Don't try to defend or fight for something if you are not in a position to do so. Better give 1 dragon up than losing an extra 3 people and possible more towers for trying to defend it

  • communicate with your team and use pings

  • call your jungler if you know you can dive him or can get a kill on him. Also tell your jungler if key abilities like ults or flashes are down for the enemy laner and where his wards are

  • be smart when buying items. Rushing t2 boots is rarely a good idea (unless jungler and +5 boots) and just a gold sink that can be better used on other stats

  • when you need to facecheck something, always try to let the most tankiest member go in front and facecheck it

  • you don't always need to win your lane. It's okay to lose the lane if you are only 1 kill and 30cs behind. Play defensive and accept it and don't try to force a comeback only to be 5+ kills and 70+cs behind in the end

  • runes and masteries. Do some research (guides) or watch some profiles from other players and get a basic idea what runes and masteries you should run on what champion. These are important to get an advantage early in lane or manage bad matchups

  • try to get used to level up your skills by using crtl + hotkey for the spell. It's faster and it can make the difference between winning a fight or not if you can quickly level up the skill in a fight.

Jungle

  • do your buffs early and don't delay them or the enemy will take advantage of this and steal them

  • respawn timers for buffs/drake/baron: 5/6/7 minutes

  • when you need to smite secure an objective, combo your smite with an ability. This means that you use a skill + smite at the same time so you have more burst to not get it stolen away

  • if you gank a lane successfully, 95% of the time it's best to help the laner push the lane so he can base and the enemy loses xp

  • if you need to hold a lane because your laner died, you can either push or freeze the lane. Try always to freeze it unless your lane is pushing anyway. In this case push it as hard as you can into the tower so it resets and the enemy can't freeze it

  • try to gank the lane that has the most cc on your team. This will give you a higher chance of getting kills and snowball the lane

  • dont waste time ganking lanes that have no real cc vs. good escape spells on enemy team. For example if you have a Nidalee mid vs. Zed and you play Nocturne jungle, unless Zed overextends a lot this gank is not gonna work and you waste a lot of time

  • only help losing lanes up to a certain point. You can maybe recover a lane that is 2 kills behind, but any more than that is usually not worth the time/effort you put into the lane to bring it back. Worst case is that you lose 1vs2 and the game gets out of control. Just ignore the lane and focus on the remaining 2

  • dont feed double buffs. This is crucial early game and can cost the lane if not the entire game. When in doubt, play defensive and don't risk feeding double buffs

  • do not counterjungle when your team is behind. It's way too risky if you don't see the enemy team

  • learn to predict the enemy jungler and countergank. This is done by watching your lanes and see who's overextended the most and just wait in the brush. Chances are, the enemy jungle will gank the lane any time soon

  • if you play jungler with a very strong lvl 6 (Amumu, Vi, Nocturne) try to use it on cooldown and gank with them to get kills/objectives

  • junglers are often still a second support. So buy wards and help your team get wards up

  • when donating a buff, press s to stop attack

  • when there is no laner in a certain lane and the minions are dying to tower, go there and take the xp/farm from it. They are more worth than jungle camps

  • don't force ganks. If there is no lane to gank for you and no opportunity to countergank, just farm up

  • don't gank a lane the moment your laner got 20 creeps at his tower. It's not worth the maybe kill if he loses all that gold and xp from the creeps

  • presence enough by buying pink wards for top/bot or showing yourself without doing anything helps your lane out by making the enemy lane play more carefully

Top

  • know matchups. It's really important for toplane and it only comes with experience

  • that said, don't pick champions because x counters z. If you can't play x, don't pick him and play a champion instead that you are familiar with

  • most of the time the first gank happens top lane. If you know you can't win 2vs2 with your jungler, don't push early and play it safe

  • a lot of people make the mistake of not pushing the lane top completely to the tower. Use this to your advantage and try to freeze the lane near your tower so can deny him farm and be safe from ganks

  • when freezing a lane, don't let it push too hard. Kill just enough creeps so that it barely pushes into your direction or you might die in a dive/gank due to too much creep damage

  • when you need to base and you can't push it but it pushes into your direction, just base and it will still push into your direction when you come back. This is better than getting denied by the enemy freezing the lane

  • when losing a lane, go tanky. If you build damage and the enemy is smart, he will keep killing you because he will have more damage than you. You won't be useful this way later on as opposed to being a tank that can still help your team

  • dont call or blame the jungler if you are unsure about getting a kill. A fail attempt will just put you even more behind

  • if they are 5man grouped to take dragon and you have no TP and can't join them, push the tower and try to trade tower for drake

Mid

  • don't forget to auto attack for harass. People in lower ELOs seem to just use a spell instead of spell+auto, which is a lot more damage

  • push for a faster lvl 6 than enemy laner if you play a strong lvl 6 champ like Annie, Ahri, Zed, Fizz to maybe abuse it and get a free kill on them

  • only roam if you can guarantee a kill. Don't waste your time going bot if you have no CC and can't make anything happen or you will lose too much farm

  • when you can't follow the enemy laner who left the lane to roam, push the lane and try to get his tower in return

  • if you have the champion to do so, farm the jungle (wraith/wolves) to get an advantage over the enemy laner

AD Carry

  • watch the health of your own minions and try to auto the enemy ad carry when he goes for a last hit. Either he will lose the trade because he goes for the last hit or he will lose the last hit

  • if the enemy bot lane is pushing hard for a lvl 2, try to counterpush and not get pushed in

  • if you can get lvl 2 before them, you can use this to your advantage and force a fight

  • it's smart to sacrifice some cs if you can harass them instead and win the lane because of this. But it's not a good idea to give cs up for free if you can't get an advantage out of it

  • watch the enemy items and try to trade with them if you know you can win. If you have a Doran + BF vs. 2 Doran + Lifesteal + Boots, you have a lot more damage and should win a fight. Be smart about something like this and use this to your advantage

  • if you have sustain by having lifesteal or with your support and the enemy doesn't have sustain, go for a lot of trades to slowly but surely get them low and force them out of lane

  • focussing the support is often a better choice if you can burst him down and the enemy ad carry has a strong escape that makes killing him hard. If you are a Graves+Blitz lane vs. Sona+Ezreal, grabbing Sona and going for her is the better choice

  • keep your farm up! dont stop farming just because you killed the tower and mid-game started

  • when teamfighting it's often better to play safe and hit what you can hit without putting yourself in danger than going for high priority targets and die

  • that doesn't mean you should focus the tanks all the time if there are other targets availabe to you that you can safely hit

  • practice orb walking and move between attacks to position yourself while still doing damage in fights

  • hit the towers when you are sieging late game and you can hit it. But don't risk getting caught so better safe than sorry

  • it's good to get defensive items when you are ahead and you can rely on your team to do damage

  • if your team doesn't have a lot of damage and your team is behind, you can't afford to get defensive items or you won't be able to win teamfights due to a lack of damage. You need to risk relying on your position and pray to survive

Support

  • you can often win or lose the bottom lane by your playstyle alone

  • your auto attacks hurt a lot early levels, so use them on the enemy ad carry (or support) when they go for a last hit and are out of position

  • your main job in laning phase is to show presence. This is done by actively harassing them

  • remember to keep your wards up and tell the ad carry to back off or be careful when you leave the lane to ward or need to shop to get new wards

  • pink wards apply a lot of pressure. Use them and tell your jungler to gank especially when you are behind in lane: go get the pinks

  • when you need to base, help your ad carry to push the lane if he wants to leave the lane too but dont screw up his cs and attack minions that he is attacking

  • your #1 priority should be vision and map control in mid and end game

  • this means that rushing a sight stone is often your best choice

  • getting gp10 is okay but still remember to get your wards to be safe in lane till you get your sight stone

  • I see a lot of supports (especially Zyra) getting damage items. Thats fine but don't neglect vision for it

  • an early oracles in mid game can snowball the game a lot in your favour

  • if you have oracles, tell your team to group with you so you can clear the wards safely

  • just because you have sight stone doesn't mean you should stop buying regular wards. Keep buying and placing them

  • when you are behind in a game, a good tactic is to regain control of your jungle and hope for picks so you can get back into the game. This is done by buying oracles and a lot of wards and hope for a picks

  • if your jungler doesn't do it, keep timers for at least drakes and baron and tell your team when they're up

  • try to keep up in xp. Don't leave a lane when there are many creeps and soak up the xp

  • don't use your skills in teamfights instantly but instead save them for when you need them to peel for your ad carry. Using a random Janna Q won't help your team as much as having it available for when a Riven tries to assassinate your ad carry


Basic tips for each role (Reddit)
http://www.reddit.com/r/leagueoflegends/comments/1oui1z/basic_tips_for_each_role_from_a_diamond_player/