Scout your neighborhood to see how other homeowners have painted their houses. It is generally a good idea to reflect the adjacent styles and paint colors to avoid a jarring paint job that sticks out from every other home on the block.
Research the classic color schemes of period homes, if yours is one. An Arts and Crafts bungalow may not have much curb appeal with a Victorian gingerbread color palette.
Go for complementary colors that contrast but have an underlying harmony. Red, yellow and blue are primary colors. Green, orange and violet are secondary colors. Complementary colors are a primary color and its opposite on the color wheel, the colors made by mixing the two remaining primary colors. For example, the primary colors red and blue make purple. The complement to purple is the primary color yellow. Red's complement is green -- yellow and blue. Blue's complement is orange -- red and yellow.
Choose a dominant and an accent color for lively contrast that doesn't fight itself. A melon bungalow with pale green-turquoise trim and a gray shingle roof is vivid but balanced.
Vary hues to keep the house from looking like a circus poster. Use a creamy yellow on the siding and paint the front door a deep blue-violet. The trim can match the door or be a much lighter shade of the complement, an almost-gray lavender. Paint shutters to match the trim.
Use a paint sprayer for the siding to save time and labor, or use large brushes and rollers to cover a large area with each stroke. Tape trim and shutter edges to protect them from drips or smears. Use drop cloths on foundation shrubs, a porch or over the front door.
When the house is painted, celebrate by planting annuals that match your new house colors along the path leading up to the front door.