If by commercial you mean working for commercial General Contractors, as versus maintenance work for property management, a good way to break in with a GC would be on tenant work - painting walls, door, frames in office or retail build-outs - versus large base building or shopping centers. These are small enough jobs for them to risk hiring a new guy. Find out who the GC's are and approach their estimator in the office so you can get on their bid list. A lot of GC's have places on their websites you can go to fill out a new subcontractor form and also see what they are bidding on and even download the plans in .pdf files.
You will need to be able to read plans and give complete bids "per plans and specs". IF you are not good with blueprints, one way might be to team up with a drywall contractor who already has an in with GC's. They are doing all the takeoffs for you - sf of walls, door counts, etc - and the two of you could sell a complete finished package. When I was a GC, I loved to hire a combo drywall/painter sub because I could look to one person for the complete job...and the good looking walls. No finger pointing between the trades.
Lastly, I hope you can carry the job. Cash flow on commercial work can be very tough.