What is the most logical next event?

How to clean and maintain a tuba
Read all warnings and prepare containers of water, etc.
Before starting.
Remove and disassemble all slides and valves, remembering how they go back together.
Take the body of the tuba and set it on top of a towel in a bath-tub full of warm, not hot, water and a little mild, non-abrasive soap. Rub gently with a washcloth to remove all yucky stuff.