This all comes down to the rules.....1. references....does the contractor have them??? I ALWAYS furnish all my prospective customers them....no excuses...2. insurance....again, I always furnish proof....3. Read the proposal carefully...I ALWAYS list materials down to tape used, the brand, the grit of sandpaper, the manufacturer, etc....its INEXCUSABLE to not list all of these items....I am a member of the PDCA, the Painting and Decorating Contractors of America, the foremost authority in the coatings industry and they also approve of what I listed....if you do not follow these guidelines, you will NOT get a job reflective of "professional". Look for the PDCA where any painting contractors are, if they are not a member, RUN!
To win work, contractors generally have to bid against other suppliers. To make an accurate bid, they estimate the time and materials required to complete the job. They measure the area to be painted and discuss the type of finish the customer requires. They assess the quality of the surfaces to work out how much remedial work they must carry out before painting. They might have to remove old paint or wall coverings, or repair cracks and other damage. They also calculate the cost of any essential equipment, such as scaffolding for exterior walls.