Twin Peaks is one of my all time favorite shows but it's a hard sell. The second season isn't very good and neither is the movie. I'd say that in season 2, after the killer is revealed you should commit to watching everything having to do with the FBI, police, or Briggs family in some way. Everything else you can kinda tune out for cause it's not that great (though, I actually enjoy the Nadine stuff). You'll def want to watch the last 2 episodes fully though.

Then you should watch the movie + The Missing Pieces (a movie of deleted scenes). You could watch the first couple episodes of The Return if you're really curious and then go back to watch the movies but it's generally recommended to just watch the movies first.

The Return is one of my favorite seasons of television. It feels like the culmination of Lynch's entire career