Agree on cost of labor and cost of material, for a total project cost.
- Be educated on your options for materials. Also be comfortable asking your contractor any questions you have through the course of the project, but especially when regarding materials and cost. This is your flip, be there, be aware.
- Allow for margins of increase of materials, but not labor, for cost. The contractor gave you an estimate, try to stick to that as much as possible. This will of course have to be judged situationally as you do run into surprises in almost any flip.