I'm reading Joanne Sharpe's most recent book, The Art of Whimsical Stitching. She recommends that you first practice free motion stitching with a pen and your sketchbook. Drawing continuous patterns, without lifting your pen, is a good way to "build muscle memory that will kick in when you move to the sewing machine." This advice worked for me, but I need to do more. I found that I enjoyed it too - there was something about not lifting the pen that made it more enjoyable than other doodling.