You pretty much get some fun free time to farm up a TINY bit. Then, if you play it right, you can surprise harass by walking into the bush, activating Q, then leaping onto the enemy and deal damage with the rest of your combo. Since Rengar does so much damage, you can instantly win lane unless you are up against something like Garen or Vlad... otherwise you pretty much have tons of fun.

It's also important your other team mates to good. If you see someone falling behind on your team, try saving your ultimate to leap onto your snacks and get yourself a nice clean kill (or even better, give it to the carry). This will increase your chances of victory from high to even higher.

Just pick off people. But if there are any SUPER fed enemies and you do NOT have your core items, stay back a bit and avoid their focus.

Really easy. Takes literally one kill to keep you rolling. All you need is your movespeed to get you around. Takes literally no time at all to kill someone and move on.