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.
You cannot tell when a modern slot machine will hit because the outcome of each spin is random. No matter how many times a machine has spun, and no matter what the outcomes of those spins were, the probability of the next result remains the same.