Step One:Gather your materials - I like purdy brushes the best, which you can buy at the hardware store, but any decent brush will do. Ideally you should give yourself plenty of time for the paint to dry between coats, so keep that in mind.
Step Two:You should prime and paint your base coat. I like to give my base coat a full day at least to dry (a couple of days is more ideal).
Step Three:Tape off your area. I use little pieces of tape to help guide my lines so they're all parallel to each other (that keeps me from stressing over using a level).
Make sure to press down the tape all along the edges. I just just my fingernails... very high tech, I know.
Step Four:Using your base coat color, dry brush the edges of the paint. You don't need to glob it on - just a dry coating (should be dry to the touch in minutes). This is the key to straight lines... any paint that's going to seep under the tap will be the same color as that stripe so it won't show. It also acts as a seal for the tape, so none of the other color will bleed underneath the tape.
Step Five:Using your contrasting color, paint nice downward strokes. Do your second coat when the first one starts to dry.
Step Six:Remove the tape when the paint is dry to the touch, but not cured all the way through. If you wait too long after it dries, you might pull off big chunks of paint.