01. If it doesn’t look human, it probably isn’t.
02. When encountering alien species on earth, remember: sympathy is overrated, and empathy is impossible. Automatically assume hostility. When encountering alien species off-world, try not to be a dick until you have to.
03. Talking to a potentially hostile alien life-form doesn’t always help, though sometimes it does.
04. Even if it looks human, it might not be. Never assume a human shape isn’t just a host.
05. Creepy people are creepy for a reason. Children are automatically creepy and are much more prone to accepting contact from alien life, hostile or otherwise.
06. Sometimes humans are the most alien of all.
07. Never question someone immortal, nearly immortal, or just bloody old. Especially if he has really great hair.
08. Get your snog on while you can, but try not to fall for someone of another species. Especially if you work for a top secret organization that specializes in alien technology and neutralizing potential alien threats. Do try not to shag the opposition.
09. However, do stay as close to them as you can. Unless they’re trying to kill you, which may or may not be obvious.
10. If you think you hear or see something, you probably did.
11. Really do try not to get separated.
12. Bring an extra flashlight.
13. The things in the dark are real.
14. Don’t turn your back. Don’t look away. Don’t blink.
15. Stay out of the shadows.
16. On the other hand, bright lights tend to be less friendly than you would think.
17. When in doubt, run. In fact, “run” should probably just be your default setting.
18. If your phone stops working, run. If the lights go out, you know what to do.
19. Learn how to use a gun, but it probably won’t do you much good.
20. Sometimes it’s smarter just to shoot to kill and ask forgiveness later. Or not ask forgiveness later.
21. Sometimes you just gotta drive a car into a building.
22. Never leave your keys in the ignition.
23. Never underestimate the value of a well-timed kick to the crotch.
24. Avoid London on Christmas. Avoid Cardiff in general.
25. If you find yourself in the midst of a particularly horrifying situation and/or you realize it’s the 51st century, blame Steven Moffat.
26. Never underestimate the power of human stupidity (cf. SEP)—nor of human courage and innovation.
27. Be clever. Use that unstoppable gob.
28. Each person has their own time at which to die. Trying to prevent the inevitable is a bad idea. Bringing people back to life is an even worse one.
29. The universe is full of strange and wonderful things, and some really horrible things, too. The past can be as strange as the future. Life is impossibly sad. But that’s life.
30. If you haven’t told someone you love them and you feel you should, for god’s sake TELL THEM ALREADY.