I only give commendation if a player does his/her job well and treats others with respect.
This also involves greeting the other party members and explaining things if someone is new to a dungeon.
People who try to do a speedrun although one or more party members are new or miss the equipment, will get nothing for sure.

Tanks:
- keeping aggro
- positioning
- grabbing adds
- keeping debuffs up
- checking healer MP and party HP before the next pull

Healers:
- keeping everyone alive
- dealing dmg if there's nothing to heal
- keeping buffs up and getting rid of party debuffs/dots

DDs:
- Monk positioning (I hate monks who keep standing on a position) and debuffs/dots
- Dragoon positioning and debuffs/dots
- Bards using songs when needed and debuffs/dots
- evading attacks which can be avoided
- LB at the right times