1 - inactivity. Your medal count = 0, you haven't donated or received troops, and you're at the bottom of the active list. Or perhaps, if your stats go as follows:
Troops donated: 25
Troops received: 450
--> That stat tells me you're a selfish person who doesn't want to help.
2 - I was promoted to officer because I was active, and my stats currently are:
Troops received: 300
Troops donated: 900
Medal count: 1400
I've also taught my boys what units are good to send, and which ones aren't. (wookies are garbage at level 5+)
3 - Look at medals obtained, activity, and troops received/donated. Higher numbers good, low numbers bad.