Consider the climate and sun
Light colors reflect more sunlight and help keep the house cooler, which is useful in hot climates. Dark, highly saturated shades fade faster from UV exposure. Use good-quality exterior paint suited to your climate.
Check your neighborhood rules
HOAs, gated communities and historic districts may have rules about allowed colors. Check with your city or HOA before buying paint so you don't have to repaint.
Outdoors, color looks lighter
Sunlight makes colors look lighter and less intense than on the paint chip. That's why it's smart to choose one or two shades darker than what looks right in the store. Paint a large sample on the wall and look at it at different times of day.