Cutting brushes to the right size can also be helpful. Since dark colors show through light colors paint the lightest colors first when possible. Also, allow enought drying time before painting second coats and other colors. Certain areas of a model will require masking. When covering an area use a tape that doesn't stick too much.
Tape known as frisket tape is a good choice.
When painting over a masked area remember to stroke away from the tape. Spray paints are best suited for large areas. When using spray paints be sure to have adequate ventalation. Beware that spray paints can coat much more than intended and should be used carefully. Spray paints will look great when applied in multiple thin coats.