CMJ used to publish a printed resource guide that cost about $99/year. It covers radio, press, A & R, Radio Promotion, Publishing. I used it for years to great effect. It also tells you all the college radio stations info, including wattage, format and student population. You can use this to target what stations to mail your disc to. Now it's only available in on-line form.
http://www.cmj.com/company/faq.php#dir5. It's worth looking into.
I've been cold-calling labels, distributors, managers, music departments of film studios & publishers for 20 years off and on. Also, "cold-mailing" press kits followed by a cold call. Now and then you'll get a reaction out of someone. I've received quite a few emails and letters from the effort of "cold-mailing". You might only get a 10-20% success rate out of the effort, and it may feel like a message in the bottle mentality. You'all also spend quite a bit of money doing it.
I've also had situations where people I don't even know pass a disc along to people they know in the business. Then you get a call or email out of the blue.
Once I met a guy at a gig whose sister was married to the guitarist of the Psychedelic Furs. A phone call and a press kit later, I was corresponding with the Furs guitarist and we were discussing plans to get someone prominent in the biz to take us under his wing and possibly set us up with some kind of deal.
When we were with RedEye USA (distributor), they gladly provided me with an extensive mailing list that covered many important areas.
Ultimately, what I'm saying is you have to put yourself out there as much as you can afford to with the public, press, radio, and labels. A lot of your packages may end up in the trash can unopened, but that's the risk you have to take unless you can find someone willing to represent you to the industry.