Spend a little "thinking" time. Decide what you want in the focus fabric, (the main fabric). Choose one with several colors in it and then pick your secondary colors from that piece of fabric. For instance if you pick a floral fabric you will have lots of choices for secondary pieces if you use the colors of the flowers or leaves, etc. If you make something with only a couple of colors you will need to consider using the colors from the fabric or using something in the same color but lighter or darker. You can always use white or black if you cannot get enough color from your focus fabric. Look in your wu ilting books and magazines for quilts you particularly like...is it the colors or the attern that draws your attention? If it is the colors you could use them in your quilt.