Jacqui Gehrig (or is it Gehring?) has a great class on using the walking foot. Personally, I like the original class better than the second.
One take-away is to work slowly when using the walking foot. I recently was reminded of this when I sped up my SID and the layers started to shift. I slowed down and no more shifting.
When sewing with curves, make it gentle curves. Those go much easier than tight curves as you don't have to lift/readjust the foot as much.
It is REALLY important to have a taut sandwich to keep things from moving. When I use 505 basting spray, I iron the sandwich from both sides. When using pins, I generally pin fist-width apart and make sure I don't put any pins in the way of my quilting line.