There's an achievement for letting your group of survivors grow to a certain point, so being reckless or negligent towards survivors and neighbours could leave you without enough survivors on the map to complete it.

One of the characters involved in the mission might die off-screen it's just the nature of the game.

'Home on the Grange' of the 'Quentin and Becca' missions is missable by making the wrong choices or waiting too long to help them out.

When you hear Lily calling on the radio about someone turning seriously ill, get back home ASAP.

'Mercy shot' is missable and potentially devastating to your home base.

It almost always triggers when you're not on another mission and when you are close by so get over there stat!

'Trouble at the courthouse' is missable if you don't get there fast enough.

Making a wrong choice in the Wilkersons storyline will make you miss the achievement so check out the guide whenever you deal with the Wilkersons.

There's an achievement for performing a special killing move called 'Double kill', one of the few characters who can learn it is Marcus so make sure that he (or another character that can learn it) chooses that specific skill.

There's an achievement for completing 50 missions with Marcus, so it goes without saying: use him a lot but don't let him get killed!.

Marcus state of decay