Well, you may catch a lot of grief from teammates who are hoping for more of a presence from you, but if you are honest with your team in the beginning, it will help. Let them know that you are learning how to jungle, and tell them that you are not super confident at it yet. Offer to ward for them some, be willing to share buffs (second/third buff, depending on how much you need them for your levels, gold, and clear, how well your laner is doing, etc), try to secure objectives like dragon and rift herald (or at least keep vision on them so you can keep the other team away from them) and just be sure to know what your specific champions are best at.
If you have someone like a Yi, then you really don't have much early game presence anyway, and your team should know that. But once you have two items, you start being able to do yi-things, and you can split pretty much anytime, as long as you keep vision on Baron/Rift/Dragon so that you don't lose them because you are on the other side of the map.
I understand your fears. I reaaaaally do. I'm a complete and total support main and have been since season 3. The first few times I had to jungle, I was absolutely terrified, and I felt like every time I ganked, I was just a buff delivery system for the enemy laner. But I picked two champions, one AP and one AD, and started working on them any time I had to jungle. And the more I played them, the more I began to get a feel for which clears worked best, which items I preferred, when I could gank, when I shouldn't, and even when I could consider invading to counterjungle. I would even make custom matches with 3 enemy bots and practice "ganking" them, just to give me some idea of the damage those champions could do to my champion if I used the runes/masteries I was testing, and went that hard for a kill. I don't find it quite as embarrassing to die to a bot that no one sees or knows about as it is when I die in a match and everyone saw my failed combo and the guy living with 10 hp.
