Identify any sprinkler heads, power lines, cables or lawn ornaments and mark them with spray paint or a flag.
Mow your lawn, then heavily water it the day prior to aerating as the soil needs to be soft and moist when aerating.
Using the power aerator, aerate the lawn in at least two different directions perpendicular to each other to insure good coverage. Be careful on slopes and near landscaping.
Run the power aerator in the morning when your lawn is cool and moist (but not soggy). Aerate in the spring, late summer or early fall.