Next time you tackle a big exterior paint job, try using a power sprayer. Start at the bottom and work your way up, so you apply paint to the underside of clapboards or shingles. Use even, steady strokes that overlap. And apply a thin coat first as a primer. Allow to dry and apply a final coat the same way, from the bottom to the top. For trim paint, use a brush.
For more on paint, consider:
Choosing a Paint Sprayer
How To: Use a Paint Spray Gun
5 Common Painting Mistakes-and How to Avoid Them