I like to raise the platform to the highest incline and put my pace at 4.0. You will need to hold on to the handles in front of you, keeping your elbows slightly bent. This may seem like cheating put it is a great way to burn a lot of calories. I will alternately let go of one hand and then the other to give my arms a rest. You will workout your upper body as well.
One tip: Make sure you change how you use your treadmill from time to time. Our bodies learn to adapt to certain exercises so change the incline and speed to get the most out of your workout.