Stay in the shade as much as possible. Start at the top and work down. Do the siding before tackling the trim. But if a wall is mostly trim, as shown at right, paint that first. Keep a wet edge as you work to avoid leaving lap marks. Postpone painting if heavy rain is likely within 6 to 8 hours after paint is applied.
"If spray painting, always back-brush or roll the wet paint immediately after it's applied. By doing this, you'll ensure that the paint is the correct thickness and is worked into every corner, nook, and cranny." —Rich O'Neil, Masterwork Painting & Restoration