Check to see if the ground is frozen by attempting to press a cultivator into the soil by hand. You cannot aerate a frozen lawn because the spikes will be unable to penetrate the surface of the soil and the soil will be unable to soak in water after the procedure.
Rake the lawn with a garden rake to remove any sticks or rocks that would slow or prevent you from being able to effectively aerate the soil.
Gather the debris collected by the raking and remove it from the lawn.
Water the lawn with a garden hose and wait 24 hours to commence aerating the soil.
Start at a corner of the lawn and walk behind the aerator in as straight of a line as the contours of your yard will allow to the edge of the grass.
Turn and align the spikes of the aerator so that that they overlap the first path. Walk behind the aerator along the edge of the first path until you have reached the end of the lawn.
Repeat the passes over the lawn until the entire yard has been aerated.
Rake the lawn to break apart the remaining plugs left by the aerator.