Ask HN: What is the best process to learn a new language?

I'm looking to learn Spanish. I live in Costa Rica right now so that helps a lot, but there are so many different language learning apps + websites + guides + books etc. I am learning a decent amount but I am struggling to keep up with the speed of locals talking.

I watch a decent amount of Netflix shows in Spanish, but most speak super quickly as well.

I'm in between using Memrise (free) or Lingvist (paid... quite pricey for an app too) right now.