Easy. Easy. Easy.
Use masking tape to tape around your pot. Spray with spray paint. I used a glossy black. Use whatever color your heart desires. Place a piece of cardboard under your pot to keep things clean while spraying.
One more coat of spray paint. Make sure you spray inside the rim up to soil level.
Let it dry and then peel off that tape! Touch-up any uneven places with a paintbrush. You can spray your spray paint into a piece of crumpled newspaper -- it will hold a nice little puddle that you can use a touch-up paint.