If there's something specifically awesome happening that people tell you about, that would be great of course. Or if there were 313-listers who would be tour guides and translators, awesome.
But I've found generally that in a strange city, finding a record store and going through the free papers and flyers to be the best bet. I don't know anyone in Croatia, but it would be worth trying to scare someplace up there to do a laptop DJ set. From what I hear Slovenia and Croatia have really enthusiastic dance music scenes.
