Paint the edges of the structure first because they often do not receive an adequate amount of paint. To avoid runs and sags, paint surfaces on the horizontal plane whenever possible. Spraying in and around corners often presents a problem, and practice is the only way to solve it. If you re in an inside or outside corner, spray it first and then blend the paint in with subsequent strokes. This gives you better coverage with less paint, and it brings out the brilliance of the other colors.
White primer serves the same purpose.
Do not try to cover darker hues, especially red, with a lighter color. Red should always be the last coat sprayed. If you re applying more than one color, before shooting the next color let the base coat dry for the time recommended by the manufacturer, usually at least 12 hours. Some polyurethane manufacturers recommend a week to give the paint time to cure, and then they suggest lightly sanding the area to be painted so the second color will have good tooth adhesion. When applying trim you ll need to mask the areas where you don t want the trim color to go.