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.
Pachinko parlors are widespread in Japan, and usually also feature a number of slot machines (called pachislo or pachislots) so these venues look and operate similarly to casinos.