There are quite a few things that go into making a decision about NPCing or PCing early events. A lot has to do with the Chapter's dynamics. Some chapters are awesome in teaching NPCs. Some chapters are awesome about taking new players under their wings and helping them get started.
I was fortunate enough to hook in with a awesome team in its early days with players who had done table tops and other LARPS and had done Alliance (NERO, back then) before I joined them. We've become one of the larger teams in the Alliance, and we are one of the most awesome teams because we are friends both in game and out of game.
I read the Rule Book, front to back (VERY IMPORTANT BEFORE YOU PC OR NPC) and had plenty of opportunities to consult with my mentor, Stephen Duetzmann, for a while before I wrote my character history and planned my initial character (thanks, Steve -- you got me started right).
But if you are not fortunate enough to have a team to roll with which has at least a little more experience, and if the Chapter you will playing is not awesome with new PCs, you might want to NPC. As an NPC it's easier to ask out of game questions, learn the rules, earn some build, and come into game as a PC with a better idea of what kind of character you want to play, and have more first hand familiarity with the rules and a little more starting skills than as a brand new 15 Build character. As a new player, you can always be that "I don't know anything" guy ... if that's what you want to play.
In any case, here's my advice:
Buy the Rule Book and read it throughly. Then go back and reread the stuff that you find interesting and awesome.
Ask questions of more experienced players. Lots of folks here will be glad to give you phone time so you can ask questions. While these boards are active with some great and very helpful people, there's nothing like talking with people who play the Chapter you will be playing to get your start.
Don't be afraid to make mistakes in the beginning.
Either PCing or NPCing as you wish, but play as often as you can so that you can gain experience and get familiar with role playing within the ruls system. The more you play, the less the rules get in the way, the more fun you will have.
That's my best advice.