If C, use the the one your project uses the most.
Personally I love Allman style, but that is not what my friends use: http://www.freebsd.org/cgi/man.cgi?query=style&sektion=9
Pick one you like: http://en.wikipedia.org/wiki/Programming_style http://en.wikipedia.org/wiki/Indent_style#BSD_KNF_style