HAH! I know the feeling. Most priority targets are divers that need to be focused once they commit to an attack, the makers help you know immediately when they're attacking. The whole point of priority targets is that you change focus from the monk you're attacking to the red mage that is now in range.
It goes without saying that if priorities are out of range that you focus DPS > HEALER > TANK.

On the flip side, anything that "goes without saying" is player experience dependent. So maybe more so be mindful of what your team should know at your current rank.