Position yourself on one side of the bed.
Sleep in this same spot of the mattress nightly for a few weeks.
Position yourself in the center of the mattress. Sleep in this spot nightly for a few weeks.
Repeat steps 2 and 3 on the other side of the bed nightly for a few weeks.
Wait a few months and then rotate the mattress. Remove all bedding, lift the mattress up and rotate so the top of the mattress is at the foot of the bed. Repeat this every few months.
Check if your pillow top mattress is double-sided -- if it has a pillow top on both the top and bottom sides. If so, flip your mattress every few months and repeat steps 1 through 5 on the other side of the mattress when flipped.