I've been playing brass instruments of one kind or another since the middle of 4th grade (1968). I started on baritone horn, took up trombone in seventh grade, and started playing tuba in ninth grade. I still play all three instruments occasionally, though lately I've mostly been playing tuba.
In college, I took euphonium and/or trombone lessons from these people:
The one who dies with the most horns wins!
Click on an instrument to find out more about it.
Here are some links to brass-instrument-related sites that other brass players might find interesting: