When I started on the treadmill I walked at a lower incline at around 4.00 mph. Then I decied to try differant variations to see what worked best for me. Right now I walk at an incline of 11 at 3.9 mph and about every 5 minutes I run at 5.3 mph for 2 minutes. While walking I do hold on. But very lightly only to keep my balance. I find that I burn more calories this way.
Then after 67 minutes on the treadmill, I do 20 on the stairmaster and then head to the weight circuit for my toning.
You might want to try differant variations and see what works best for you. I tend to get into a zone where I really push myself hard.