Stabilizers can only take out so much camera shake so the user must also turn their body into a shock reducing machine.
Walking and Posture:
Walking heal to toe and letting your feet smoothly roll from heal to toe really helps keep a smooth motion. You will also want to keep a straight back as a lot of people tend to hunch over. Keeping good posture will lessen fatigue.
Holding the Stabilizer:
Keeping the rig (your arm) extended away from your body will help keep things nice and smooth because your arm will take out some of the shake before it reaches the camera stabilizer.
Video courtesy of www.SteadiGO.com