Kpen asked for other suggestions. I thought IMHO this would be an excellent and useful post topic.
It will depend on the generosity of the professional players who may feel they do not wish to divulge secrets.
As the least qualified, I'll start with stuff everyone knows:
1) (As previously) Hold back in the loudest passages until everyone else is tired and then push out a huge tuba sound as the note ends. When the basses, bones and timps are playing ffff nobody can't hear you at all anyway. (Yes, I can hear the shrieking denials). But as they die off, then you pounce (in tune, without hooting). The final effect is of the timps still bashing and the chord ending with a firm tuba bass note.
2)Bribe the nearest bass/bone whatever player to poke you hard at the end of those interminable rests (esp Borodin Te Deum [tedium]). You can sleep, read, smartphone, learn Sanskrit, post on tubenet- do so much.
3) Study the whole score really carefully to see how you are meant to fit in and with whom. Yes, many composers simply stick us in as extra bass trombones and noise machines. But many also know what a tuba is. Photocopy bits of full scores.
4) Always, always, always play Bydlo on a euphonium. It sounds wrong and falsetto on a bigger instrument even when played brilliantly. (Yes, I can hear the shrieking denials). This is a young tenor lamenting the fate of the Polish peasantry - who were nicknamed 'oxen' - 'bydlo'. It was written for a tiny 'peck horn' French tuba in c. Go play a cello concerto on a string bass. Yes, it sounds great but wrong.
5) If possible consider triggers which spring back very fast on the 4th, 1st valve slides etc. You can use them almost as valves then.
6) Make sure your horn is built sharp, then pull it out to just ring in with that band's pitch.
7) Be certain you are always perfectly in time with exposed notes. The most minute anticipation is sometimes necessary in a sluggish hall, opera pit, hall with closed curtains, place where you are seated far out etc.
Anyway those were some obvious ideas just to arouse the wrath of the real pros and spur them into action.



