For this tutorial, I used a 12 inch length of 1/2 inch ribbon. You will need more ribbon for the larger sizes.
Fold your ribbon in half and hold the center point between your thumb and pointer fingers. Take the bottom ribbon and fold it over the top and hold it, you will simply continue to pick up the bottom ribbon and fold it over the top ribbon until the ribbon is completely folded. It should be a nice little square shape of folded ribbon when you are done. When you are have folded it as far as you wish to fold, hold on to the last two folded squares of ribbon and let the rest go. I should then look like this: