How to get commendations:

1. Play a healer
2. Perform decently as a tank
3. Perform exceptionally well and competent as a DPS
4. Have a good/funny portrait


If I were to categorize them by priority, I'd go with

1. Have a good/funny portrait
2. Play a healer
3. Perform decently as a tank
4. Perform exceptionally well and competent as a DPS