Listen up, LiAngelo and LaMelo Ball -- now that you're official residents of Lithuania, we're hookin' you up with a superstar athlete who can tell you all about your new country!
UFC champ Rose Namajunas has been out there a bunch to visit her Mom's Lithuanian fam ... and told TMZ Sports exactly what they gotta do.
Avoid -- all the booze and partying.
Enjoy -- a) the basketball-loving Lithuanian fans b) the fact that people speak English pretty well and c) the smokin' hot chicks.
Bottom line -- Gelo and Melo should be fine ... if they only ball out on the hardwood.