It totally depends on what you are fighting and when.

For Soloing:

When fighting monsters I could easily defeat, I would bellow nonstop (no
stacking).

Around level 20-21, I started having a lot of problems fighting monsters that
were "dangerous." I began to twist healing and warsong, to 1) make me kill
faster
and 2) make me live longer. When the mobs got down to 1/3 to 1/4 life, I'd
switch to bellows and warsong (if my health was okay)

For Partying:

Melee:
I would take preferance to singing Anthem, and switch to healing (and step
back from the fight to avoid the shit list effect) with my mandolin.

Fighting magic users:
I would sing/twist the rhythm songs (to boost resistances) and anthem.