Need Help W/ Teamfights

I'm having trouble. So I've been playing jungle recently and I've been having a ton of fun with it. I usually do fairly well in laning phase by helping out and getting lanes ahead but I end up being almost useless in team fights. For example, I was playing Elise earlier today and I did great in laning phase, but felt useless in team fights. I would try and wait for the right moment to go in but I'd end up getting cc'd and completely obliterated. The only champions I know how to team fight well with are control mages. When playing a tank do I just focus on peeling? Or when I play someone like Nidalee or Elise, should I attempt to flank and focus on one target? Thanks for your time. Any tips would be great. (: