When spray painting, after shaking the can for a minute and then shaking it again for another minute - hold can upright 8” – 16” from surface. Press trigger or nozzle and begin covering the surface lightly in a steady back and forth motion, slightly overlapping each stroke and shaking the can a few times as you paint. This will give you a nice even finish. You get blotches of paint when you hold the spray in one area for too long.  If you get blotches and want to sand it to start over. Wait for the paint to completely dry. If you sand too soon you will create a gummy mess that will be hard to remove.  If this happens, use paint remover to remove the paint, clean well and start over.