Haven't really seen this pin pointed in this discussion yet, but most books will tell you to have a Lawyer send your Demo to a Label.
They will throw out all other unsolicited demo's unless usually from a Lawyer.
Asside from that, my old band was being looked at by Road Runner Records By 4 different sources.
We had a Manager of the band Sinch in Philly contact us from the internet exposure.
We had a Road Runner Scout that contacted us after we posted comments about our band on the Soul Fly Website Forum.
We recorded our demo CD at a Studio in Sacramento who apparently was friends with Monte Conner and wanted to give our demo to him.
But the one that really got us connected was a Manager of our friends band in LA who was looking for a new metal band to push.
He got our Demo CD and gave a call to Mike Gitter at Road Runner who then showed us to Monte Conner.
Now each of those is an example of either who you know or putting yourself out there and getting lucky that someone noticed you.
Unfortunately the moment you get label interest, they start telling you what they dont like about your band and what they want to see from you.
Thats when the band members start slitting eachothers throats pointing fingers at who is holding the band back and then someone either quits or gets kicked out and the band either moves forward or dies on the spot.
Work hard and build a hype. Push your band like a $2 whore and if you are as good as you think you are it will happen.
Have your shit together as a band.
Bust your balls on a good "performance" Recording.
Promote.
Network (Bands, Managers, Studios, Lawyers).