1. Inspect your mortar. Is it crumbling or otherwise deteriorating, or are there gaps that need to be fixed? If so, address those before you even think about shuffling through paint chips. You can probably seal minor holes yourself with spackle or caulk, but major damage means a call to a mason.
2. Scrub. Paint never adheres perfectly to a dirty surface. Use a stiff-bristled brush and a little dish soap diluted in water to clean the brick thoroughly, then wipe it down with a dry cloth. Let the bricks dry completely before you start painting.
3. Select the appropriate tools. Brick is heavily textured, so you'll need painting supplies that can handle its pits and crevices. Choose rollers with a long nap and press hard as you roll to push paint into tiny holes, or use a sprayer for the most even results. You'll probably want a brush to take care of mortar lines and cut in around doorways or windows. Because of brick's rough edges, cutting in isn't as easy as it is on a smooth surface, so use a narrow brush that you can manipulate around bumps and crags.
5. Pick your finish. Brick often looks best painted in a slightly glossy finish, which highlights its detail better than a matte one and makes it easier to wipe clean. Use a 100% acrylic paint and roll or spray on one to two coats of your chosen color.