Making clean paint lines between two colors doesn't have to require a steady hand or special equipment. This technique is very simple and requires only paint, brushes and masking tape. This time, however, you will be controlling the bleeding paint and using it to create crisp lines that precisely follow the edge of the tape.
Step 1: First Color
Step 2: Taping
Step 3: Bleed Line
Make sure the lower edge of the paint feathers softly away so you won't see a thick edge of paint later on.