before you get your ult, you cant really hope for kills unless your enemy is exceptionally stupid. just keep poking with your q and basic too keep them away. Once you get your ult though, you can kill almost anyone as long as its 1v1 and there is no turret. just initiate with R, then Q, then throw in a W where theyre running to slow them, and use E as much as possible. if you dont kill them right away and they run, just keep ulting on them. This is also for ganks.

assassinate ppl as often as possible, if they stray from a group even a little bit, initiate with your ult, and keep hitting them with combos. if your fed at all, then you can initiate into groups too, just make sure you have backup.