I found that the people that I met who are best at speaking many languages at a conversational level will tell you that it's easy, that it's nothing special. They don't follow any scientific theories and are more concerned with what they wanna be saying than the fact that they are using another language. Little mistakes don't matter but you can also notice that they don't make the same mistakes after some time.
It also helps to be creative, like for when you don't know the word 'dawn' you'd say 'uhm, when the sun comes up' and continue with what you actually want to say.
--> a crazy good example of a language learner in MMA is Junior Dos Santos!!! in the Tuf with Lesnar he could hardly speak english and at the end of the the season he was already great. Must be an intelligent guy I thought then cause it really stood out.
A terrible language practitioner is Cain. His parents are Mexican, he has good spanish pronunciation (better than mine at least
) but whenever you see him trying to use his spanish it's no bueno
On with the heavyweights, guys guke Minotauro or Bigfoot are good, I think, at not having a huge vocabulary but they are able to say anything they want by describing stuff or using easier words. That's way more important than using a lot of big words or 'learning vocabulary and grammar by heart'
number one point IMO is having a reason to learn that language. knowing what situations you want to use it in and then practising for that -> like with Martial Arts!
Everybody who is good at Martial Arts has a motivation (fitness, flexibilty, self defense etc), I think nobody who just goes to the gym and practises 20mins of jab-cross in the mirror (aka studying vocabulary or grammar) gets good at fighting. same goes for the language.