You should be able to harrash enemy with huge early damage of your Q and that is not hard to hit In the best cases you should be able to outzone enemy and deny their lasthits with the positioning of yours.
For support soraka is good because she can give mana and she has insane heals, but janna is also good bacause with janna's shield your Q hit's them like hell.

For early laning, faster u get sheen the better, it hurt's them like hell.

With Ezreal it's normally easy to avoid bein killed by ganks bacause of "double flash" and with that i mean Flash itself and ezreals E ability.

When going in teamfight's you should come a bit late and try to land few q's to enemy ad carry and try to position yourself so that you can either chase by jumping with ur e or to get the **** out from there by your e and flash :)

REMEMBER, that if you have already 2nd bloothirster, and you are not late from others you should be able to outlifesteal almost any champ with your Q

Q - your main damaging ability, use it as often as possible because it redces the cooldowns of all of your skills by 1 sec per hit.

W - Use this on enemy AD - carry due the fact that it reduces their attackspeed.

E - Your another Flash use it to chase down enemys or to run away, and to position well in teamfights.

R - Use this to steal dragon or baron or kill fleeing enemys or to just farm for your BT, remember that this skills cooldown is reduce by 1 s per q u hit so it will be up often if you use q often.