Tone vs technique
I believe that the most important element in tone is having a clear mental image of your desired sound. Many young brass players concentrate so much on technique that they lose sight of the fact that the sound is the most crucial factor in their success as musicians.
The great opera composer Giuseppe Verdi, when asked to list the most critical elements for success as an opera singer, gave three answers: "The voice, the voice, and the voice." With brass instruments, the key to success is your sound, your sound, and your sound. In other words, outstanding tone quality.
How to find a great sound
The best way to find your optimal sound is to listen to CDs of great players and go to live performances whenever possible. I believe that it is essential for every young brass player to do this, not because you necessarily want to imitate everything about a single player, but because it is so important to have a deep mental arsenal of sounds from which to assemble your own ideal sound.
My final word on tone is this: Listen constantly to great hornplayers! Aside from diligent practicing, this may be the single most important thing that you can do to improve your playing.
Horn Tutor : An online learning resource for hornplayers

