Start out passive, work your way to counter attacks, then aggression, see how he reacts and proceed accordingly. For example if you notice him playing passive too feel free to W,E combo the minions and push to his tower making sure you are well warded and aware of the map. If he is aggressive let him push and combo him every time he jumps on you E>W>Q, notice how i end with q, it is because your Q refreshes your aids so make sure when you are 6 you have to E>W>R and q to start or end to get maximum effectiveness in your abilities. If it is casual then don't push too hard and punish him when you have the chance to once every while being conservative with your mana. Notice how he plays when he's about to get a gank and notice how you play when you are getting a gank, you need to adjust your play style to mask your gank and realize exactly when he;s gonna get a gank before it happens.