What would you like to make someday? I looked for some patterns I hoped to make in the future and started cutting some sizes for those. I'm sure at some point I will have more than enough to make a few different scrap quilts.
What I end up cutting from my leftovers mostly are 2-1/2" strips, 2-1/2" squares, 4-1/2" squares, 5" squares, 6" squares. I don't bother cutting triangles usually, but if I have leftover, I save them. I do save some narrower strips if I think I will use them in paper piecing or other small projects.