Although you don't have to pick colors that match, you're likely to be happy with the results if you pick colors that have relationships to each other on the color wheel. The color wheel lays out colors in a way that you can see their relationship by their placement on the color wheel. Warm colors are on one side of the color wheel, cool colors on the other side. Complementary colors are situated across from each other, and analogous colors are side-by-side. Designate ahead of time that you want colors that are all warm, all cool, complementary or analogous to give you a starting point for choosing your patterns and fabrics.
Colors have different moods and psychological states associated with them. Choose colors that embody the person who will be using the quilt. Soft pastel colors are appropriate for small children, nurseries and feminine bedrooms. Bolder, darker colors are appropriate for adult bedrooms and living rooms, depending on the decor of the room. If the person who will use the quilt has a favorite color, choose fabrics of that color and fabrics in colors related to the favorite color.
A dominant color is the prevailing color of a color scheme, and the accent color is a lesser-used color, usually a complement of the dominant. The dominant color usually is presented in multiple shades, to prevent the design from becoming too simplistic. By choosing a two-part dominant and accent-driven color scheme, selecting colors for your quilt will be a relatively easy task.
Quilts take a lot of time and effort. If you're not making your quilt for anyone specific, go with your gut instincts and pick the colors and fabrics you like best. You're most likely to be happy with the quilt if you've designed it from fabrics you love.