Most record labels will not accept what they call "unsolicited" demos. One of the best things a new artist can do is to find a good publicist or find someone who has been in the business that can consult them to the things they need to do.
I've been in this music business for over 12 yrs. When I work with a new artist, I help them put their packages together in a professional manner that will help make people take them seriously as artists. Then we target press, and build press placements, because that is what's going to make labels take you serious, the fact that you've been in different magazines, newspapers, ect. My website is www.planetmeridian.com, theres a lot of info there that talks about things new artists can do.
You will need someone as a go-between to help you submit your music to different labels, they won't take music from just anyone.
Let me know if you have any more questions. Feel free to request me next time you have a question.
If this has helped, please click accept.