Specify whether the contractor or you will supply the paint. Check Consumer Reports' paint ratings: In its tests, some relatively inexpensive paints performed better than more expensive paints and cost $10 to $20 less per gallon. But keep in mind that most paints will resist cracking, peeling, mold and mildew. Who does the painting — and how well they do it — is more important than what's in the bucket.
Thorough preparation is essential to ensure a good finish. Contractors might have to fill cracks or holes and remove old paint if it is badly worn, peeling or flaking. They remove all paint and apply a suitable primer to the bare surface. If the existing paint is in reasonable condition, they clean it and rub it with abrasive material to provide a key for the new paint. On new surfaces, such as bare wood or fresh plaster, they apply a suitable seal, followed by a primer coat.