Determine how much primer the project will require. One gallon of primer will cover about 350 square feet of a smooth surface. A rough-textured wall needs one gallon for every 250 square feet.
Use a dish rag or cloth, dish soap and warm water to scrub the entire wall.
Wait for the walls to dry before applying the primer. Use a roller for open areas and brushes for smaller, finer areas. Apply the primer in even strokes.
Use a piece of fine sandpaper to lightly sand the walls after the primer has dried. This will allow the paint to go on more smoothly.
Choose a color for your walls. Choose a color for the ceiling a few shades lighter than the wall paint. Most paint stores have samples that demonstrate the complete spectrum of a given color.
Cover the floor with newspapers or plastic ground sheet, which is available at most home improvement stores. This will prevent any paint drips from seeping into the carpet or staining the floor.
Paint the walls with the darker color. Rollers will be ideal for most of the wall but switch to a medium-fine brush for corners and small areas. Work in 4-by-4-foot sections. Use consistent, vertical strokes.
Wait a few hours for the paint on the wall to dry.
Use a ladder to place tape on the wall near the "crease" where the wall and ceiling meet. Get as close as you can to the ceiling without actually covering any of it. This will keep the ceiling paint from bleeding over onto the wall.
Cover the floor with newspapers or plastic ground sheet.
Paint the ceiling with the lighter shade. Using the same technique as with the walls. Employ rollers for most of the open spaces on the ceiling and default to brushes for the finer areas. Work in 3-by-3-foot areas. Use consistent strokes.
Allow a few hours for the paint to dry.