The best slots strategies consist of increasing the size of the bet after losing. You can do this in small increments after a loss, or increase the betting level after five consecutive losses. The goal is to win more from a larger bet and thus cover the previous wagers.
It's all a matter of chance. There are no blackjack- or video poker-like strategies that can cut into the house's mathematical edge. Odds on slot machines are unchanging. There's nothing you can do legally that will change the outcome, though scam artists sometimes have succeeded until caught, arrested and imprisoned.