Not because he's a genius, but just because he spends a little time doing a little crafty homework. If you play the slots, give this approach your consideration. The odds of lining up three matching symbols are better than the odds of lining up four. So, choose three-reel machines. The exception is video slots which may allow for multiple pay lines.
Most online casinos offer odds similar to or better than Vegas and Atlantic City.
But if you want specifics, contact the individual casino and ask for the info. Check the odds of each machine. If you're on a roll and think you have found the proverbial 'loose' machine, play your bankroll through the machine once but do not play any of your winnings. When you get change to play slot machines, give the teller a small tip. Then ask for pointers on which machines she would recommend that you play.