Choose the best quality paint you can afford; it lasts longer. Experts estimate that the outside of a house should be painted every 5-7 years, but less-expensive paint may start peeling or fading in 4 years or less while really high-quality paint will hold up a bit longer. Better Homes & Gardens describes and compares the different types of exterior paint while FastFacts.com reviews specific brands.
When the primer is dry, caulk all small joints (less than ¼-inch-wide) in the siding and trim. Most pros use siliconized acrylics—paint won't stick to straight silicones—but Guertin and O'Neil like the new, more expensive urethane acrylics for their greater flexibility and longevity. O'Neil stresses that it's shortsighted to skimp on caulk. "If the joint fails, you're back to square one." Guertin uses the lifetime rating as his quality guide. "I don't expect 35-year caulk will last 35 years, but it should last longer than a 15-year caulk." Thornton House Painting