What is your champion pool? Can they get kills? Can they counter? You want a champion that has the kill potential. The champion that can roam, stun, and kill. What is your play style like? Are you too passive waiting for them to mess up and when they do, do you mess up and not capitalize on it? Pick a champion you're strong with and be aggressive with him because you want to get fed. You want to carry. You know you're strong at level three? Go in. You are strong at level three. You push your wave and hit level two first? Go in [dont tower dive damnit]. You hit level six? Go in. How about you poke the enemy champion and ping for top gank [if they dont come, fuck em, you poked em low enough. Go in].
Don't overstay, you are low? Go back and miss the CS but don't give them the kill and miss CS.