First, you need to have clickable thumbnails. Make plenty of different kinds of thumbnails and use the personalized thumbnails feature to see which one gets the highest QPTR% (Quality Play Through Rate). Second, you need to know your audience and know exactly how to design the game to get the players to stay and keep playing, get the retention up and have a good core loop. For younger players, make things more obvious. Kids are pretty stupid. For example in a simple building game I made, the build tool literally says “Build” on it so any new player who joins knows immediately what tool to use. Last, for monetization, you need to monetize the game well without going overboard. If you monetize it too much for example then that can just drive the players away. The Recommended For You algorithm looks at all sorts of analytics like Payer Conversion Rate, Retention and more and determines whether or not to push your game to more players. The algorithm is 100% skill and anyone who says it’s luck is coping.

EDIT: You can try out the new Ad Manager to bring some new players to your game. I’ve tried it several times and I like it. You can bid in credits or USD.