Which way to take for Multilanguage

I‘m planning to do some tests with languages. First I want to think about the concept and which way I should take.

• I could make a translationfile and maybe bind these infos to smth like $$LangVars$$ where I use the proper translation? (Filebased)
• Store Language Variables for texts ans buttons into a database? (DataBased… lol)
• Set Language via URL Parameter or Browser Lang. detection and then pass/read Language translations via ServerSession? (Yess Sessions…)

Do you have any experience with that multilanguage? I mean I‘m not talking about Arabic language (right to left), which would make stuff even more complicated. But what are your best practices with that, where you struggle and which way is good to go ?