Teen at work, with questions!

So I work at a restaurant in a small town, and make minimum wage, pay period every two weeks, and I'd average my checks to come out around $240 every time, sometimes a little lower, little higher, like I said, average :P

With all of this, how much should I be setting aside? What percentage of this should go in a "keepsake" or a "save for a rainy day" area? And what other advice could anyone give me?

I just want every single financial move I make to lead me in the right direction for later on in life, whether its when I work at a fast food joint in my teen years, or 20 years down the road when its something major.