This tip comes from Sarah Noreen, an excellent printer who designed the December page in the 2011 PA Letterpress Calendar. To facilitate registration, she does test prints on tracing paper.... SO smart! I know I've shown some of you how to do tests on copy paper and compare alignment using the lightbox. It's the same idea, but this way is so much simpler! Just do your print on the tracing paper and then line it up with your actual paper to see where it'll print in relation to your paper's edges or previously printed colors!
Sarah's card had a little cutout window, so she used the tracing paper to place her pretty border around the window: