Piecing is easy. Get good quality (non fuzzing cotton) neutral color thread because no one is gonna see it anyway. I use a lot of off white or black, depending on the color base of the quilt top.
For quilting, I look at the colors I have as the primary colors of my top. I'll choose a variegated thread in the color family I am using and let the design flow or if I want to hide the stitches, choose as close to a color as the base, only a bit darker. It hides it well.
tim in san jose