Asking for commendations is lame.
Giving advice when not asked is bothering.
Giving not asked advice with the goal of getting all commendations is lame and bothering.
As tank, 9/10 times I get at least 1 commendation. Since the healer is my bf, we usually give ours to the DPS who really impressed us. And if he's not healing in my party, I almost never commend a healer, but again, the DPS has to be extraordinary.
I personally give advice just when I see the message "one or more party members..." blah blah. And I make it short and to the point.