David: Start with the local SBA office. That is the best place to begin, especially when it comes to the various “set aside” designations: 8(a), HUBZone (Historically Underutilized Business Zone), DVBE (Disabled Veteran Business Enterprise), etc.
They can also put you in touch with your local state agency responsible for the parallel state programs. California has a state designation for minority, woman owned, disabled vet, etc.
The Federal government is required by law to spend fixed percentages of their contract dollars on various designations, so research is key.
I work with quite a few government contractors in the military and federal markets and gandalf is right: You need to be careful with whom you work. A lot of the large players have figured out how to game the system using these designations to their advantage, so research the markets, the players and the history.