This achievement is awarded by completing the Wilkerson brothers' storyline. A lot of players have had problems with the missions not showing up so here's an in-depth walkthrough.
*** Spoiler - click to reveal ***The Wilkersons live up and to the right of the church where you establish your first real home base. You can drive a car through the forest behind the church for a shortcut to their farm, just drive carefully and look out for any steep falls. Drive right next to the graveyard for the smoothest ride.
Getting the missions:
There are six missions in total, the first one comes after you've rescued Lily's brother from the farm. Some missions might take a few in-game days between them, so it's a good idea to do them as soon as they show up. If you do, the last ones should pop up around the time you've started doing story missions in the town where "The law" lives.
Some missions in the game are affected by vicinity, so if you've already relocated your home base, try doing some missions or scavenge runs up in the church village. If you want to be completely safe, hold off on relocating your base until you've completed all of the Wilkersons' missions.
Quitting the game to the xbox dashboard and starting it again might make the missions pop up. The game also counts "offline time" so you could quit the game, do something else and come back and it will count as time passed in the game.
Having "missing survivor" missions might impede other missions from popping up, so get those survivors home!
Warning
The Wilkerson storyline is linear so make one wrong choice and it ends. Turning down any of the Wilkerson missions (except Nervous Survivor) will stop the storyline completely and you won't get a second chance, your only choice is to start a new game. Failing missions will also stop the storyline.
1. The Old Farmhouse - Get the Doc!
The mission is about getting the doctor for your friend Ed who's sick, so if you dallied around and let Ed die you might not get this mission. SHAKES MUGWUMP and MattiasAnderson have reported that even though Ed died, the second mission in the storyline still triggered, so this seems to be patched now. If it doesn't, you could try getting rid of your infirmary, wait for someone else to get sick and see if it triggers the mission.
This is the trickiest of the bunch, you'll need to defend the Wilkerson farm from several hordes and at least one Big un zombie. Get a gun with high fire power and clip size, stock up on plenty of ammo and head to the farm. Board up the windows and shoot the zombies between the boards. The easiest is one shot to the body to make them kneel and then another to the head. The Big un needs a minimum of around 15 shots to the head to lay down. Or you can get out of the house and just beat and molotov them, they'll generally pay more attention to the windows than you.
2. Accusations
Head up to the Wilkerson farm and confront Job.
3. A Helping Hand
Go to the Wikersons farm and give a stranger a ride.
4. Nervous Survivor
The stranger you gave a ride needs some ammo, his farm is about in the middle of the map, go there and donate five crates of ammo. You can also refuse to give him the ammo, the succeeding missions will still become available. IMPORTANT! If you accept to give him the ammo but you don't have the five required crates currently in stock, the mission will fail and it will stop the storyline. So if you wanna be a good samaritan, make sure you've got enough ammo first. Press UP on the D-pad, then go to your home base menu. The number next to the bullet icon tells you how much ammo you have in stock.
5. Unwelcome Guest
One of the Wilkerson boys will show up at your home base and ask for a favour, just say yes.
6. Neutral Observer
Head to a farm at the right side of the map, and agree to drop some people off for the Wilkersons. Get in your car and drive away and the achievement will pop!