To get started you need the basics:
Business License (Usually required by the city/county u operate out of)
General Liability Ins (Most primes want 1Mil/2 Mil umbrella coverage)
Workers Comp if 3+ employees. (If all your techs are Independants/subs, then you may not need WC, but understand that there is a fine line between Emplyee and a sub. Contact IRS, they have publications etc that can help you make the determination for tax purposes.)
Obtain an Employer Tax # from both the IRS and the State u r in, for tax filing .
State License ( You may be required by your state to have a license, look in the blue pages of your phone book for a state contractors commission or likeness. call them and they will tell you if one is required.)
Vehicle Insurance.
Most of this stuff can be taken care of in 1 day, sounds like alot, but it really isnt.
Hope it helped,
J