Obviously you can just choose 10 random contracts and complete them in order to unlock this, but the quick way is to do a contract search for
* ITA Facility
* One Target
* Pistol
Then deliberately choose a contract where the victim is Luca Wood (you'll have to open the contract to confirm the name); about half to two-thirds of your results will likely be contracts for him. He is the guard patrolling right in front of the gate at the starting location. Play the contract, shoot him in the head, hit the exit button.
Repeat the search and choose a different version of the identical contract (the one's you've completed have check marks); this same contract keeps getting created by different people over and over again because it's one of the easiest ways to get
so there are lots of this identical contract available.
Once you've done this 10 times you'll unlock the achievement. Each of these contracts can be completed in 10-15 seconds, so you'll spend a lot more time on the loading and searching screens than the actual game play.