Christopher has given you some sound advice but I want to carry it a bit further. . .
If you get the reputation of doing freebies for friends or even charity, that's about the only work you're going to get offered. It is a rut many of us get into because we are told early on, to do this very thing. There comes a point however, in which you must start charging or you will be abused. . . especially by friends & family.
If a friend is having a casual mixer it's perfectly fine to do some pocket tricks at no charge and for the sake of having some fun. However, if said friend wants you to bring in a 20 minute program (or more) you need to demand some form of compensation UNLESS a.) you're willing to do it for the sake of practice & breaking things in; or b.) there is a charity situation attached to the event (which would include school type performances for their kids, church programs, etc. ).
Yes, there is a C. to this scenario and that would be events in which local VIP types are going to be guests at the event and you'll be able to distribute business cards, etc. and actually "network" with the movers & shakers of your community. If you can impress this type of crowed you will get job offers and frequently decent payment offers vs. a set fee. This really does depend on the quality of your work however and how you present yourself -- comfort level and rapport is everything to such people.
The thing is, don't build a reputation for doing this sort of thing, not even for charities. It will come back to get you and in short time, so always charge something, even if it's just your fuel and materials costs. . . if a prospect won't cough up $50.00 you don't need them.