You have your short list of contractors whose track records seem clean and whose work ethic looks responsible. Now it's time to stop looking back at past work and start looking forward to your project. A conscientious contractor will want not only a complete set of blueprints but also a sense of what homeowners want out of a project and what they plan to spend. To compare bids, ask everyone to break down the cost of materials, labor, profit margins and other expenses. Generally materials account for 40 percent of the total cost; the rest covers overhead and the typical profit margin, which is 15 to 20 percent.