It has been designed in a way that ensures each spin is entirely independent of previous results. So, outcomes of the past have no bearing on the future. And as it's the same for every user, slot machines are 100% fair.
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.