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.
When playing blackjack, you want to beat the dealer's hand. The dealer is the only person you need to beat, so while other bettors can join you, they are all competing to beat him or her. Blackjack has the best odds of winning in any game, with a 49% chance of winning.