This is a simple achievement that can be achieved fairly early on in the game. The first job board that you come across is in the main town of Wellsprings. The board itself is located directly across from the clothing store in the back part of the town.
All you will need to do is check the board every so often and do the missions that pop up on the list.
The missions range from simple fetch quests to keeping people alive by providing sniper fire from affar.