This was kinda on the old forum.
Think up specific CM based achievements, be it for marines or xenos.
Here were some of mine:
BIG IRON ON HIS HIP:
As a M5 RPG spec, kill 4 T3 xenos.
:m NEED MEDVAC AGAIN!
As a combat medic, medvac 10 marines, with at least 5 being from your squad.
Pounce THIS:
Buckshot a lurker who misses their pounce at you.
Make it rain:
As a squad leader, call in 3 CAS strikes, and 2 OBs.
Checkmate:
As a captain or commander, plan out and execute a successful pincer attack.
Plan B:
Get a kill with a pistol in your sidearm pouch after you run out of ammo.
Savior of the broken, the beaten, and the damned:
As a squad marine, rescue 5 marines from a resin nest.
Well supplied:
As an requisition officer or cargo technician, send down 8 crates of supplies to the marines.
Bait and switch:
As a marine, lure a crusher charge into defense, and then close a plasteel barricade, trapping them in.
Cat and mouse:
As a sniper spec, prevent a boiler from firing gas 15 times.
I know kung fu:
Kill a queen with a punch.
Built to last:
As a squad engineer, set up and defend a fallback position for 15 minutes under constant siege without losing a single barricade.