Any movie can have a protagonist, but when you're looking for prototypical heroes, fantasy is the place to turn. It's chock-full of earnest young men and women who right wrongs and fight evil... and sometimes commit the most bone-headed moves imaginable. What is it about being heroic that causes people to turn in their common sense card? Just in case you ever find yourself in a situation where you need to be a hero, here are some tips to remember.

1. Don't Ignore Warnings
Young Jared Grace (Freddie Highmore) from The Spiderwick Chronicles (2008) accidentally discovers a hidden chamber, locked inside of which is a book. Not just any book, mind you, this one is sealed, with a great big honking note warning against opening it. Now, let's review: Sealed room. Sealed trunk. Sealed book. Warning note. Why in the world would he think that opening the book is a good idea? I mean, does he go around drinking bottles labeled "Poison"?

2. Stick to the Plan
The titular character in Prince Caspian (2008) does so many bone-headed things, but this one has the worst consequences: In the middle of a daring invasion of his murderous uncle's castle -- an invasion that is going perfectly, I might add -- Caspian learns that his uncle killed his father. The smart thing to do would be to continue the plan and then string his uncle up after securing the castle. Caspian, however, abandons his role in the invasion to demand whether it's really true, resulting in the widespread slaughter of his army. Nice play, revenge boy.

3. Be Careful What You Wish for
In Excalibur (1981), King Arthur's (Nigel Terry) best friend Sir Lancelot (Nicholas Clay) is badly wounded in a duel. Arthur begs Merlin (Nicol Williamson) to save him, "No matter what cost." There are times when that kind of request is totally appropriate, but you've got to really mean it. What's the cost here? Lancelot and Guinevere (Cherie Lunghi) get it on. You said "No matter what cost," so quit your whining and keep ruling Britain. Do not fall into despair and let the kingdom fall apart. Heck, import the custom of Ménage à trois from France and then you can have your cake and eat it too.

4. Think Before You Act
The Maitlands (Alec Baldwin and Geena Davis) in Beetlejuice die and get trapped in their own home. Worse than that, mortal humans are inhabiting it. The choice to scare the mortals is a good one, but honey, putting a floral sheet over your head just isn't scary. (Neither is it a good idea to summon a bio-exorcist your case worker specifically warned you against). I mean, you're dead, surely you can come up with something to scare humans. And if not, enlist the help of a real professional who doesn't share his name with an insect.

5. Don't Split Up
No matter how often you tell people this one, they'll still insist on splitting up when searching for the big nasty. Take a mild instance of this, like in Ghostbusters (1985) when the gang splits up to hunt down a, well, ghost. Fortunately, the worst that happens is that Venkman (Bill Murray) gets slimed, but if it had been a deadlier monster? It's just not good ghost-busting practice. Searching might be slower en masse, but at least you can work as a team to actually take the baddie down.

6. Listen to the Experts
Stanley Ipkiss (Jim Carrey) is almost smart. In The Mask (1994) he finds the titular item that completely changes his personality, wardrobe and physical abilities. Wisely he decides to consult a mask expert who informs him that the mask is a representation of Loki, the Norse god of darkness and mischief. So stop wearing the thing, right? The mask freakin' possesses you when you put it on. Guess not. Here's a tip: Anything that forces you to lose control is not a boon whilst facing down villains and rescuing damsels in distress.

7. Don't Walk Away From the Villain
I couldn't pick just one movie because every single hero does this. Why is it that when they've got the upper hand, they've won the fight and the villain is down on his or her knees, the heroes feel the need to walk away? Is it to prove what a good person they are? Maybe. But what it really proves is how dim-witted they are: The villain always, always stands up to backstab them. If you aren't going to kill the bad guy, you should at the very least cuff him.

What other utterly bone-headed things have you seen heroes do?

Mary Robinette Kowal is the winner of the 2008 John W. Campbell Award for Best New Writer and a professional puppeteer. Her first novel Shades of Milk and Honey is being published by Tor in 2010.