Take dance lessons, duh.

Ok but I'm not talking about couple dance/etc. How do you get into this weird, undefineable dancing that takes place at clubs/raves ?

I've absolutely NO knowledge on this topic, no idea where to start. Most people tell me to just "go for it" (since there's no "rules" for freestyle dancing) but I'm pretty sure I'd just align myself with the attempts over at /r/whitepeoplegifs and I don't see how that would be helpful :p