It does take some planning. Rather than using scraps, I completely cut a 'bonus' quilt and work that in between. Right now, I'm working on christmas gift quilts made from used men's shirts. For my bonus quilt, I am using brights plus white and doing the Bonnie Hunter Patches & Pinwheels.
http://quiltville.blogspot.com/2005/...pinwheels.html
I took a day and cut all the pieces for the patches quilt, placed (not sew) them into twosies and put them in a basket by my machine, where I can grab them as needed. Since i chain piece, I usually only have 1 or 2 bonus pieces sewn when I go to the ironing board and I just press them too. The color combo is totally different from the main quilts I'm working on so it's easy to keep them apart. I'm making four Christmas quilts and i figure that I will have the blocks for my bonus quilt done at about the same time.
My advice would be to set aside a whole day and cut those scraps (or a bonus quilt). You are not going to do it if you keep running out.