Once you've assembled a list, Tom recommends that you make a quick call to each of your prospects and ask them the following questions:
Do they take on projects of your size?
Are they willing to provide financial references, from suppliers or banks?
Can they give you a list of previous clients?
How many other projects would they have going at the same time?
How long have they worked with their subcontractors?
The answers to these questions will reveal the company's availability, reliability, how much attention they'll be able to give your project and how smoothly the work will go.