I work as a teller when im not in school. I'm 20, and most of the people there are older than in their teens. I think your best bet for getting into finance at that age is to try to find some area of a bank that doesnt deal directly with money like a call center or something similar. Most banks have positions where you would be basically taking customer calls, like telemarketing but they call you instead. This might be a good inroad into a banking job when you get older.