I traced and measured out each panel and drew the pattern onto tissue paper. I have a cheap roll of iron-on interfacing which I iron to the back of all the pattern pieces. It's just makes them more durable and less likely to tear, as I have to pin and re-pin each piece 6-8 times to make enough covers for my chairs.
I've written down details such as how much fabric I need and the steps I need to follow to sew the covers in my sewing book. The notebook is covered in brown kraft paper and I decorated the front of the book with this dress form graphic from The Graphics fairy.
Now I just have to find the right fabric (at the right price).