Articulation
In this section
How do I articulate cleanly on the euphonium
Support the note with moving air, let the tongue define its beginning, and coordinate that release with the valves. Practise slowly enough to hear whether the attack, pitch, or fingers are actually causing the blur.
What should a daily euphonium practice routine include
Build each session around sound, flexibility, articulation, and actual music. A short routine you can repeat most days will do more for your playing than an elaborate one you rarely finish.