Painting contractors work in the property maintenance sector. Depending on their skills and resources, they might specialize in painting different types of buildings, including houses and apartments, or commercial properties, such as offices, factories or retail outlets. Some contractors work directly for property owners; others find work through real estate firms, rental agents and property maintenance companies.
EPA's Lead Renovation, Repair and Painting Rule (RRP Rule) requires that firms performing renovation, repair, and painting projects that disturb lead-based paint in homes, child care facilities and pre-schools built before 1978 have their firm certified by EPA (or an EPA authorized state), use certified renovators who are trained by EPA-approved training providers and follow lead-safe work practices.
Some contractors work on time and material others on a firm contract. I would never hire the former and am leary of the latter. A contractor may low-ball a bid to get the job planning to make a killing on change orders. If you say good morning to them, they charge you extra for that. If the contract is not very, very specific and extensively fleshed out or if they display their change order schedule prominently on top, show them the door.