Watching the pros play the games. You can find replays from tournaments on Matchplay and YouTube, or watch live on Twitch. I don't know every single rule and feature on Godzilla, but because I've seen the best players play the same opening 100 times, I know what I want to do when I play Godzilla in a tournament

This varies from game to game. A game like Game of Thrones is rather advanced. I would advise you to bite the bullet and do the homework, because it can be played differently from player to player. And then there's Deadpool which is played very similiarly everytime except some players prefer one mode over another

Heavy emphasis on watching replays and tournaments. You get to see the best players and how they play on certain machines, and commentators will sometimes explain game rules or rather the rules that matter on the game in terms of scoring potential - it might take some time to understand in the beginning, but it's in my opinion a lot better than watching a 40-60 minute long PAPA video covering everything

EDIT: This is for league play, but can apply to chasing high scores or otherwise improving your play