It is much better wherever possible to try and meet people. If you send a demo in, try and back it up with a meeting or a phone call, and follow it up a few days later. For television, having pictures to accompany your music is essential to demonstrate your ability to write to picture. Keep your ideas short, four or five stunning tracks, no more than a minute long are enough. Be hypercritical of your music, listen to the quality of what's around and see whether yours matches up.
Aim for the best, the most exciting, upbeat, uplifting and unusual. Something that sounds appealing in its own right. There are reams of atmosphere tracks around, so avoid this route.