I would say first to get in tune with the scene. That means go out to events, get to know the regulars, the resident DJs, and even the promoters.
Biggest mistake many DJs make is to just show up to a busy event, hand a promoter a demo with a short introduction, and then leave. It just screams that you only care about playing a set and not about being an enhancement to the event.
Make sure when you make a demo IT FITS THE EVENT. I don’t care if someone thinks dark trippy dubstep is utterly cool, if he’s handing a mix of that to a promoter pushing poppy EDM, then expect to never hear anything back.
If you have materials, then make a press kit. I’d even tell you to venture into making it all as digital files and give it to a promoter on a thumb drive they can keep.