Once you've properly prepped your walls, the actual painting is easy. Follow these steps in order, and don't skip any of them. Wait until the first coat dries before deciding whether you need a second one.

1. Clean walls.
Remove dust, dirt, and grease spots (which can ruin a smooth finish) with water, a little mild dishwashing detergent, and a cellulose sponge. Rinse walls with clean water to remove the soap residue.