Prime. Dark colors, stains (once sealed), and previously unpainted surfaces (drywall, spackle, etc.) will need a primer coat, usually white. NOTE: most paint stores & home improvement centers will now tint primer (at no charge) to match fairly close to the color of the finished coat, that way two coats of primer need not be applied. Although not all surfaces need a prime coat, skip this step at your peril! Dark colors will likely show through the first -- or even the first couple-- topcoats of paint. Sealants and unpainted surfaces like spackle patches will absorb or repel moisture in a topcoat at a different level than the areas surrounding them. Applying a good primer coat will help even out these differences. Primer equalizes a wall to a uniform surface. It's like erasing a canvas before drawing a new picture. Although some will argue the point, you generally don't need to spend a great deal on primer or buy special primer. A cheap, 5 gallon (18.9 L) bucket of plain, flat white paint will usually do the trick and cover a large area. Give your primer at least 24 hours to dry (follow its instructions) before applying a topcoat.
Most pros don't bother cleaning brushes and rollers if they are going to use them the next day on the same job. "Latex paint dries slowly in cold temperatures," says Maceyunas. For two-day jobs, he wraps the rollers and brushes in plastic grocery bags and sticks them in the refrigerator. "Just allow the roller to return to room temperature before reusing it," he says. Roller covers are almost impossible to clean thoroughly. Most pros buy new covers for each job.