I think that it's easy to get into trouble with stippling when we try to make the stipples too small and too close together. To me it makes the stippled area too board-like and stiff. I did try some of the preprinted self-adhesive-on-the-edge sheets that you just sew over for large stippling to practice, but this was a total pain with paper stuck in the stitching afterwards, etc. Don't try these, is my advice. Just relax and practice until--suddenly, you'll get it! Take lots of breaks while you're practicing, too, to avoid getting too frustrated--practice for 1/2 hour and do something else for 1/2 hour. Let us know how you're doing with it, OK?
Dana