Umm... well, I'm sure he doesn't want to be treated like some kind of foreign species of human. And I'm pretty sure he doesn't want you rambling on and on about how much you love manga, pocky, sushi, gothic lolita clothing, visual kei, Miyavi, Hello Kitty, Utada Hikaru, Asian boys... etc. I think it's flattering to an extent but just don't overkill?
It's not rocket science though. Chances are, if he's attracted to you physically he'll give you the time of day.