There are a lot of gambling sites that rely on the skills and techniques for you to win the game, but actually that is what you should prefer to play compared to those gambling sites that only rely to the luck of the gamblers. Aside of playing you are also thinking or analyzing which is really important to maintain and boost the way we think.
Here is the link where you can learn some games that may require skills and techniques to win, and they also listed some ways for you to win:
https://www.gamblingsites.com/blog/100-ways-to-win-at-gambling-16240/There are many gambling sites that actually requires a technique or skills like poker, blackjack or any other card games. But I think, there are limited gambling sites that let you allow to play other people in different country. In card games maybe, the skills or technique are more applicable in real life than in online games since you can't see your opponents.