I mostly have been promoting through friends, Youtube, Facebook, Soundcloud, Soulseek, and forum communities. Communities like FP definitely help since you tend to get a lot of traffic when you promote yourself to people who can familiarize with you. Not to mention, helping others definitely gets you a few listens. A lot of people promote on things like Yahoo Answers, where they'll answer a question about music production or something, and include their link. A lot of producers also make video tutorials which drive in a lot of their traffic (Ephixa, Jordan Mencel, Forekast), which is what I might start doing. Deadmau5, who isn't exactly the god of EDM producers, utilized the forum/community technique and look where he's gotten to. And in my opinion, spamming just makes you look bad and most people avoid or even flag your spam.
But promotion is damn tough. Originally when I started producing, I thought it'd come naturally and so I was all towards production. Now, I spend 99% of my time networking and 1% of my time making music. Hopefully I'll get the ball rolling and get some consistent traffic, but until then I'm sorta stuck working my ass off.
The thing about EDM is... everyone loves to listen to it but very few actually like it. By that, I mean, EDM isn't really THAT popular in the US. Most people like dance music, not necessarily EDM. They like the poppy stuff that the producers collaborate with, like David Guetta (almost all of his songs), Afrojack (his collab with Pitbull), and Steve Aoki (his collab with Lil Jon). Yet as soon as Afrojack releases a standard dutch house track, only true EDM fans actually bother to listen to it. The regular audience only listens to it when they go to a club, bar, or event. They don't exactly look or even bother to download EDM as much as a fan or producer might. The same people who find your music average when they hear it on Soundcloud/Youtube might be going wild when they hear it in the club (with or without their inhibitions lowered).
And performing with EDM isn't quite the same as it might be with your average rock band. Finding DJ gigs can be tough if you're a nobody. As a college student in Albany, NY, I spend all my partying time trying to meet with the frat owner or whoever in order to land a gig. But a lot of the time they'd rather just put an Ipod on unless you're DJ Cire or some other big wig. And even though the city has constant EDM concerts and events, it's always with the larger names. Back when I played in a metal band, it was a lot easier to get a gig since venues were constantly looking for starters and the money that bands will pay to play. I usually try to just give my song to the "DJ" at the party (guy with an ipod) and ask him to play my tracks. I've gotten a few positive responses, but it isn't like the people dancing know, or even care, who's song it is.