Focus on farming and harassing your lane oponent, I recomend putting a ward at the river, near baron to prevent ganks, if the jungler is low and has double buffs, try to kill him even if you will need to use ignite and flash.

Red and Blue buff will help in the laning phase even tho it's all about luck.

In this phase you should have top lane won, I recomend you to ward the enemy red/blue, also try to help mid and roam bot, the most frequent error is stop pushing Top lane, you should push it while your enemy is base or roaming and when he comes back roam mid and bot.

Use the adventege of lost mid or bot, you can easily double kill or shut down your opponent.

You should group with your team at mid, try to take the squichies before the fight,
when they stay behind you should flash ulti Yomumu for them.

Focus on forcing an inibitor.

Your build is ready, now you should let your tank engage and while some one is focused ( xD )
focus the Adc>Mid, after that you can run away and meditate in case you are ignited and got some healing reduction efects, if you are too low dont go in try to escape or keep pushing while your team does the job.

I hope you found this guide helpfull, this will totally help you in Bronze and Silver leagues, I don't recomend using this in Gold or highter.

Summoner Crichigo, EUW.