If I had to start over I would buy more solids and blenders. I am finding I go for black a lot when looking at sashing or borders as I love the overall look. I also like white on white for backgrounds when doing applique. I guess what you are interested in quilting would be key to what you are looking for. Scrappy quilts are good for fat quarters and all the "pastry lines" (jelly rolls, cakes, etc.). I agree that scrap happens, and sometimes they are well intended quilts that just never make it to actual quilts. I separate my stash by color value so you can tell if you need more light, medium, or dark fabric.
Mainly have fun with fabrics that catch your eye and eventually you will have fabric that you love and will all work together well just waiting for that pattern you can't wait to make. This site is great for stash building with the wonderful de-stashing that goes on to make room for more new stash!