One more item to buy...
I have been quilting for many years and I think of all my items/gadgets, my most used is my Shape Cut. Can be purchased at Joanns with a coupon or just as cheap without a coupon at Wal-Mart. I have three standard size ones, one huge one, and a couple smaller ones. The small ones are pretty much a waste of money. I just bought the huge one so haven't used it yet, but the standard one measures about 15" x 18" with slots for your rotary cutter every half inch. Buy one and practice with it, and it will become your BFF. I use mine for cutting squares and rectangles, cutting strips for quilting and binding, and for squaring up finished blocks. Three things I can't live without... My dogs, my coffee and my beloved Shape Cut!