Thrifty
Win a match without purchasing a primary weapon 
Note: You can’t get any trophies in any game modes labeled “(Bots)”.

Unless you are really good with pistols, I recommend playing “Demolition”. For this, you’ll need to hope for some good teammates and some bad enemies. You can purchase anything in between rounds, except a primary weapon. Although, you can pick up and use primary weapons dropped by dead teammates or enemies. Your loadout will be reverted to normal if you die and/or at the start of a new round, so you can’t keep an enemy or teammate's primary weapon.
Ambush
Down an enemy without taking return damage 
Note: You can’t get any trophies in any game modes labeled “(Bots)”.

This will probably just happen randomly in a game; however, a good strategy is to flank the enemy team after they have captured the point in a game of “Strikeout”. Some Rogues can also purchase a $4,000 perk that makes their footsteps silent when not running. Lancer’s (not a base Rogue, see Good Company for more information) primary ability, Quick and Quiet, allows her to run faster and quieter when activated.