If you play too passively with an aggressive champ, then you are missing out on her potential. However, playing too aggressively will lead to pushed lanes where you become easy prey for junglers and you lose out on creeps.
Try to strike a balance between both sides of the spectrum. Pay attention to your creep wave to see if there are minions to last-hit, but at the same time watch your opponent's movements and land a poke ONLY if it's feasible for you to do so.
In regards to minions, don't ever engage on someone when they have a majority of creeps against your side (unless you have some heavy engage support?), because you'll end up taking a lot of extra damage that'll make it easy for your opponent to turn the tables. That's pretty much with any champion, really.