Derek Sivers really hits home here:
Early in your career, when you are searching for success, the best strategy is to say yes to everything. Reach way outside your current circles. Do it all, and give it your all, no matter how small. The more things you try, and the more people you meet, the better. (They’re a little like lottery tickets.) You never know what random tiny connection could become your big break.
He has an excellent site, by the way. You can get lost for hours reading there.