[NTG-context] Basic question on Unicode and ConTeXt

Hi, now and then I saw threads on this list dealing with specific problems of using various languages with utf-8 input in ConTeXt (processing with pdftex, NOT xetex). I know there is \enableregime[utf] but what else I needed that the output equals my utf-8 input? Could some maybe give a short and usable How-To on common examples: Greek Russian an East European language and an Asian language? (If the platform makes a difference, I'd be interested in OSX.) Thank you, Steffen