Open your PDF to Page 7 (First Studies). Play the first 10 exercises slowly. Then skip to the Articulation section. Do exercise #1 for single tongue, exercise #13 for double tongue.
It covers essential skills including scales, arpeggios, ornaments, and multiple tonguing. Arban Tuba Pdf
If you have zero budget, here is a legal, free workflow: Open your PDF to Page 7 (First Studies)
: These advanced etudes represent the "pinnacle" of the method and are often used for audition prep. Where to Find the PDF here is a legal