The first step is to pick a project that can use up your scraps. I took my inspiration from this tutorial from the Fading Charms Quilt. So messy pile of scraps? Or organised project in process?
First, I ironed my fabric scraps. I decided to use a 2-1/2" template for my squares so I could get a nice bit of pattern into them. The templace I made from a cereal box (the only reason to buy cereal really, is for the template material), and I had a pinking shears to cut the fabric as I wanted to prevent the edges of the squares fraying. Who only knows how long it'll be before I decided I have enough colour variation to start sewing.
Use the template to centre the pattern if you like, and cut out the pieces with the pinking shears, making sure to give a seam allowance outside the template.