The truth is that there is no trick to slot machines. They provide random results based on set mechanics and it all comes down to luck. With that being said, not all games are the same, so picking the right options is key, and you can still change the size of the bet throughout the session for better results.
Good bankroll management is one of the most important tips for winning on slots. Bet too much and you risk going broke before you have a chance for the luck to even out. Bet too little, however, and you risk not maximizing your profits. It's important to plan your stakes correctly.