Maybe @vincentnijman has some tips, although I feel like he was born with 6 languages installed

Haha! It definitely did not come this easilyy to me
but I had two parents who also spoke a handful of languages, I guess that helped
and I had 6 languages in high school ( if I count two years of Latin and 5 years of Ancient Greek ).

I would lie if I said that I speak 6 languages fluently because I don't but if I had to, I could make myself understood in Dutch, English, German, Spanish, Portuguese and French.