For this achievement you'll want to start and win 10 matches of Team Deathmatch.
You can either choose to head out to Online versus mode for this or you can set-up a Private match with the minimal amount of points and difficulty w/ bots to earn it much easier.
For Online it'd be wise to choose a loadout that you're familiar and confident with, cooperating and backing up your teammates, and always listening and being aware. The goal is reaching 50 accumulated kills for your team.
After your tenth match win you'll pop this 10G achievement!