Most large open source projects have their own style guidelines. For example, here's the Apache C Language Style Guide.
As a start, I suggest trawling the FAQ for the OS project you're interested in and take it from there.
Anyway, I'm sure there'll be plenty of people who'll quickly let you know if you're breaking any existing style rules in a big way! ;-)
Take heed of all the warnings, usually they are trying to tell you something useful. Don't finish up "programming by coincidence" (book excerpt) as the Pragmatic Programmers say!
Edit: I didn't realise that this was your own, new, OS project. My bad. Anyway, I'd have a sniff around some similar already existing OS projects and see if they have any style guides. Definitely, check out Steve McConnell's book Code Complete (Amazon link - sanitised for the script kiddie link nazis that roam these halls).
What I said about warnings and "programming by coincidence" still applies! (-:
HTH.
cheers,
Rob