How you mow matters…actually matters a lot!  When you mow your lawn the same direction every week you will start to develop ruts or tracks in your lawn.  This happens when the weight of the mower travels the same path every week.  Before long you will start to notice actual grooves in the yard.  This can easily be prevented by changing the direction you mow each week.  Mow at different angles, go from front to back, side to side or any other pattern you can come up with.  In the long run you wont regret it!  If you are starting to see some effects of tracking, consider using a aerator on the lawn to break down the top layer and help give it a head start.