You are an assassin but you don't have a lot of damage in the early game, try to poke with you Q and if the river is warded, you can poke with you W but be careful, it's your escape, without your W you are a free kill.

When you have your level 6, you can roam or try to snowball your matchup. When you have some kills, go splitpush and if 1 or 2 enemies go on you, try to kill them and say to your team "Take the drake" or "Take the nash" or "Take the mid/bot/top"...

You're a good assassin so use your R to kill the ADC/APCarry or a fed guy. after, try to go out of the fight and recover your spells. Go in again and clean the fight.