Keep doing what you're doing. Go out, talk to DJs, talk to promoters, get yourself known, then eventually ask for a spot, or you might even get luck and get offered one without asking. Sending out Soundcloud links doesn't really work that much if they don't know who you are.

I got my first gig at the Railway this Sunday, it's taken quite a while but that's the best advice I can give, I imagine others will pretty much say the same thing.