I'm of the "whatever feels good" group, but I agree that it is better for you to learn to move your fabric from side to side as well as forward. Doodling is a good exercise, but holding a pencil with one hand is a lot different than moving fabric with both hands. One exercise I do is to just make a sandwich, then sit at my machine and move it around. This will help build muscle memory for when you begin stitching. Also, a tip from Harriet Hargraves is to warm up on a practice sandwich for 15 to 20 minutes before you start on your project to warm up your muscles.