Exterior color schemes draw inspiration from the physical factors on and around the home, as well as traditional architectural palettes. There are a variety of elements that can be used. Take into account any stone or brick work on the foundation of your house. This can lead you to a neutral, warm grey palette. The style of your home may also be a factor. A victorian home with lots of design accents may lend itself more to a color scheme using whites and deep colors, whereas a craftsman style home may look best in muted shades. Remember that most exterior palettes are varieties of neutral.
Also look around your neighborhood for inspiration. Is there a house painted a color that you just can't stand? Remember it. Note any recurring themes that you do like as well. These will help guide you into having a home that blends well with the neighborhood. Don't forget to consult your homeowner's association, if you have one, to make sure there isn't a paint palette they prefer you to stay with.
When looking at options for your trim, it is best to stay with one crisp color all the way around the house. Trim can be used to highlight architectural interest, or blend in features that you don't like. Use a crisp contrast in color to bring out the features of your house that you like best. If you prefer to blend your trim, consider using a darker shade of the color you used on the main body of the house. Many paint manufacturers provide palettes that have a main body shade, and one or two colors to be used on the trim. If you are feeling stuck, try to take inspiration from them.
Accent pieces on a house can be the one thing that differentiates it from every other building on the street. Your front door and shutters can be a great place to add a little character without going overboard. Popular colors for these are deep jewel tones such as ruby red or emerald green, or rich hues like navy blue or an off-black. Also consider updating your accents if you want to change the exterior of your house without going to the time or expense of repainting the whole building.