"If you can sing it, then you can play it."
Having great tone starts in the mind first. If you can clearly hear the sound that you want then you have done most of the work it takes to improve your sound.
The next step would be to practice daily to slowly chip away at your ideal sound. As trumpeters we worry a lot about the separate aspects of how to play the trumpet. However, Vincent Cichowicz, says "All of the component parts of playing are merged by the aesthetic message guiding them."
In this video, I give you helpful tips on how and why it is important to:
1) Have a clear "Sound Image"
2) Listen to all trumpet players
3) Imitate your favorite sounds