Copyright the songs. Contact the U.S. Copyright Office at www.copyright.gov. Follow the instructions to copyright your songs online or by mail. Copyrighting songs protects authors from shady music producers stealing them and making a profit off of them.
Look up music producers that work within the genre of the demo being submitted. Don't send a country song to a hip-hop producer, unless there's some crossover potential. Also, find a producer that you think will work well with your music. Look at the liner notes or online information on an album you like and try contacting the music producer responsible for it.
Make sure the music producer the demo is being sent to accepts unsolicited demos. If not, hire a lawyer or manager to work as an intermediary so the music producer take the demo more seriously.
Include a letter of intent with the demo. Tell the music producer why you are looking to work with them, what kind of production desired, whether or not the songs will be pitched to a different artist, etc. Include information about your musical career.
Include a typed lyric sheet with the demo if there are vocals.
Include a self-addressed stamped envelope so that the music producer may return any materials back if he even does so.
Label everything in your package. This includes the letter, lyric sheet, CD case, the CD itself and any other information you include. Music producers receive a lot of demos, so you want to make sure each piece can be accounted for amidst the shuffle.
Before you send your demo, contact the music producer and let him know that the package is on its way.
Contact the music producer several weeks after submitting the demo, unless he has given explicit instructions not to. It can be helpful to remind him that you sent a demo in, but too many attempts to contact can be bothersome.