If your roof is a red brown or a dark brown, consider a warm color for your shutters. Colors like rust red, burgundy, copper, brick red and maroon are all appropriate. Dark red, when placed against light gray siding, creates a high-contrast look. Use a darker gray or white on your trim.
If your roof is dark gray or black, use dark gray on your shutters. This gray may have a hint of navy, but keep the shutters relatively neutral. For the trim, pick white. To add splashes of color to this relatively neutral color palette, consider hanging a flag from the porch or plant an array of colorful flowers in window boxes.
For a house with a blue-gray or gray-brown roof, neutral colored shutters -- either dusty brown or dark beige -- are appropriate. These tasteful colors add a touch of class to your home. Use cream as an accent on your porch and gutters.
A green roof is fairly rare, but if your roof has a green cast, pair it with sage or dark sage shutters. These shutters will look best on a house with a lot of natural foliage, where green is already a prevalent color. Use white as an accent, painted on a porch or around windows.