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.
Although there are a lot of people that are saying that you can't win with real money on slots, this is simply not true. In fact, there are quite a few people that have won millions of dollars from playing online slot machines.