10 Skills To Help You Survive The Apocalypse

Okay, so if your problem is an invading force rather than some kind of impact, one size doesn't necessarily fit all. You'll need to figure out the best way to combat each threat.

For zombies, most sources agree on the whole "destroy the brain" bit, so we can try that one first. If it turns out that sci-fi writers have been lying to us all these years and destroying the brain doesn't work then, fear not, you can still stop them. Even something without a heartbeat or brain will need its limbs to get itself around so reducing your zombie to a torso will certainly slow it down.

For an alien invasion, your biggest obstacle is the unknown. We'll have no idea how their technology works, or whether our weapons will hurt them. We could use biological weapons, a la War of the Worlds, and cleverly slay them using the common cold. But even then we're assuming that they have systems that are similar enough that Earth bacteria will damage it.

You could always put your faith in the idea that maybe they didn't travel halfway across the galaxy to murder us in our beds, and see if they come in peace before shooting them.

In the case of a robot uprising, you could arm yourself with an improvised EMP device if you fancy taking them on. If running away is more your style then you have a couple of advantages. Humans are incredibly dexterous and adaptable so use this to your advantage by mixing up your terrain, climbing things, swimming et cetera. 

If all else fails, you could try turning it off and on again.