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.
Each game you play at a casino has a statistical probability against you winning, which makes gambling an inadequate option for those looking to boost their income. While the house advantage varies for each game, it ultimately helps ensure that the casino won't lose money over time.