* When it appears that you have killed the monster, NEVER check to see if it's really dead.
* Never read a book of demon-summoning aloud, even as a joke.
* Do not search the basement, especially if the power has gone out.
* If your children speak to you in Latin or any other language which they should not know, shoot them immediately. It will save you a lot of grief in the long run. However, it will probably take several rounds to kill them, so be prepared. This also applies to kids who speak with somebody else's voice.
* As a general rule, don't solve puzzles that open portals to hell.
* If you're searching for something which caused a loud noise and find out that it's just the cat, GET THE HELL OUT!
* If you find a town which looks deserted, there's probably a good reason for it. Don't stop and look around.
* Don't fool with recombinant DNA technology unless you're sure you know what you're doing.
* If you're running from the monster, expect to trip or fall down at least twice. Also note that, despite the fact that you are running and the monster is merely shambling along, it's still moving fast enough to catch up with you.
* If your car runs out of gas at night on a lonely road, do not go to the nearby deserted-looking house to phone for help. Shoot yourself instead. You are going to die anyway, and most likely will be eaten.
AND MOST IMPORTANTLY:
When trying to escape from a serial killer, never run UPstairs.