Behind every stunning paint job is the primer that lays beneath it. Primer ensures that the paint sticks to the walls and retains a uniform appearance throughout. Also, be sure to clean and repair any surfaces before applying the primer.

From Home Depot:

Step 1: Tint primer for best results

Most primers can be tinted, and tinting will ensure good coverage for the finish coat. But too much tint will dilute the primer and reduce its efficiency. Ask your store associate for assistance determining exactly what you need.

Step 2: Spray roller or brush

Dampen your roller or brush to get off to a fast start. Use water for latex paints, paint thinner for alkyd or oil-based paints.

Step 3: Cut in corners

Pick your starting point and cut in (apply paint at all corners or places where walls, moulding and ceilings meet) the corner with a 2-inch sash brush or a corner pad. Cut in the first 3 to 4 feet along the ceiling, too.

Step 4: Roll on Primer

Apply the primer using a 9-inch roller with the appropriate nap. Start with a single vertical strip at the cut-in corner.

Step 5: Paint a ?W? pattern

Roll the remaining wall in 3′ x 3′ sections, working from top to bottom. Lay the primer down in a ?W,? then fill in the gaps without lifting the roller.