1.  Make your Budget.  Have a clear plan in place on how much money you are going to spend for the day & casino.  I wouldn't consider spending under $20 in any one machine.  Sometimes you need to ride a machine out for more than a quick hit.

2.  Always bet the maximum for the machine.  That is the only way to get maximum jackpots and be eligible for any progressive pots.

3.  Pick a high exposure location.  Casinos want people to see winners as it leads to more gambling.  Often the odds of bigger payouts are better on the aisle or highly visible area.