1. Is breathing part of your daily drills? Even doing 2 minutes of a flow exercise can go a long way.
2. Playing a band instrument, for the most part, requires you to fill up with more air than normal speaking volume. I usually stress with my students that "Band Breathing" is deeper, fuller, more active than "passive breathing."
3. One rehearsal technique to get kids using more air, is to have them play a musical excerpt on only one note. You can start on Concert F. The air feels the same and should be constant on every note. Then to promote greater air support, move to a low register note such as Concert Bb. Then do that musical passage at FF all on low Concert Bb. It's a "high flow note" that will get them using more air than they are used to.
I could write a dissertation on this topic, but I'll stop at those 3 suggestions.