After choosing all the fabric for a pattern, cut a 2" square of each fabric.
Get one or two sheets of copy/ looseleaf paper.
Lay the first swatch on the top left side of the paper and sew it to the paper with a basting stitch.
Place the next one below the first and continue sewing each swatch in a column down the left side of the paper.
Write any information you want next to each swatch. The fabric info from the selvage, how much you need, where it goes in the pattern like background or star points or part A, B, C, etc., and how many pieces to cut.