I usually have a pattern and then I find my favorite fabric to go with it. I often use the author of a book or magazine
that I enjoy using. I change pleasures all of the time and go from solid color choices (primary colors) to red,white, & blue, to blended quilts. I do agree sampler quilts help to obtain style, color values. Good luck beginners, keep it simpler and grow from there. The whole issue is enjoy yourself and don't let any quilt police interrupt your growing talent. It is always a work in progress.