If you are just looking to get this one quickly. Go into the Contracts menu and select Contract Search. Add the search term "Easy", set Missions to "ICA Facility - Prologue" and Targets to "1 Target". Select Go Search and you should find many that aim to kill "Luca Wood". He is the guard at the gate and therefore can be taken out with a pistol and finish the level in around 7 seconds.
If the contract is for "Christopher May", he is the guard within the booth next to the gate, so another easy one to do quickly
You must do 10 different contracts, not the same one 10 times