If it's something like Rocket League or Overwatch (fast, twitch games), there's no shortcut - maybe watching a few videos will help explain the mechanics - but

If it's something like Rocket League or Overwatch (fast, twitch games), there's no shortcut - maybe watching a few videos will help explain the mechanics - but all you can really do is practice. For most games though, reading the wiki is the best way to accelerate your knowledge of the game. Let's Plays are often pretty good, if the creator really explains their thought process.