Those sizes that were previously mentioned are great to start with. 5" and 10" squares along with 2 1/2" strips are what I use most of. Since the 2 1/2" strips are the same as jelly rolls, there are a lot of patterns for those. I belong to a charity group and we sew baby quilts for those in need and so we use almost all scraps. It's amazing how many tops you can make out of scraps.