firstly, I'm not anywhere near sending demos, but here are few tips I catched when I was thinking and learning about promoting:
When?
- you should send demos to channels and labels only when you are 100% satisfied with your sound and mix. Make your first impression count
- talking about building a fanbase, It does no harm to start collect followers on SC and Facebook even before your first song upload. It's the numbers of followers that count when you send your profile links to labels.
How?
- if you aren't established, sending promo to Trapcity, Suicide Sheep etc. is a waste of time for both sides. These channels are very picky and most of the time you need to know the guys that uploads songs there. I'd suggest 2 things: First - do some good research around the youtube and find medium/small sized channels that uploads their good music in genre you make. Secondly, try to make contact with owners of these channels, and not by sending them promo in the first message. You can show them how big fan of them you are, bring them some value from you... make friends with them
- you can reach some following even through cliché stuff like youtube comments, if stick to ORIGINALITY of the comment, not typical "I'm 12 years old bedroom producer, check my channel" but comment songs relevant to your style with something like "can you imagine this song with sax intro and in 110 BPM? Give my channel a try!"...
my two eurocents here.
-