My first scrappy quilt was on foundation and was also one of my first quilts. Can use an old sheet or muslin that has been through the laundry so it will not shrink later. Choose one fabric that you want to be your "focus fabric". Mine was a blue print. Now use up your scraps, alternating lights and darks, remembering that mediums will become either lights or darks next to the previous strip. You will need some triangles as the last piece on the foundation. You can join these blocks together or put sashing between them. This method also is learning experience in recognizing lights and darks.
This method can also be done on paper pages from phone books but then one has to go back to remove the paper so putting it on fabric is a lot easier!