Stars Playing Themselves in Movies: The 7 Make-or-Break Rules

When Seth Rogen and famous friends face the apocalypse in "This Is the End," they will join the ranks of stars who have taken on the challenge of portraying themselves (or versions of themselves) on the big screen.

Hitting that close to home, some have rise to the challenge swimmingly, while others have drowned.

Here's a guide to how an actor stays afloat while playing his favorite character of all.

1. Surprise. If you're, say, a former child star best known for playing an earnest character with a ridiculous name, such as Doogie, go smooth and slick and slightly noxious. Neil Patrick Harris did just this when he played himself in "Harold and Kumar." Then, once the world sees you in a different light and notices that you can make fun of yourself, watch your career get suited up in "How I Met Your Mother" and awards shows everywhere.

2. Play the you people think you are. This is the flip side of the Neil Patrick Harris rule. If you're, say, a former "Star Trek" captain whom audiences believe is a hammy, self-involved lothario like William Shatner, then go all out in a film like "Free Enterprise." Then once you’ve shown you can parody yourself better than anyone else can mock you, make an entire second career brilliantly parodying your own famous persona.

3. Less is more. Ben Affleck is all over "Jay and Silent Bob Strike Back," playing his star self (making an ill-advised sequel to "Good Will Hunting," alongside fellow good sport Matt Damon). But director Gus Van Sant makes a bigger, better impression as a mailing-it-in Gus Van Sant in a cameo that offers welcome relief to all the trying-too-hard scenery-chewing.

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4. Don't be in a much-reviled movie. If you only watched clips of Al Pacino spoofing his thespian self in Adam Sandler's "Jack and Jill," you might think: funny. If you had to sit through the whole movie (it of the lowly 3 percent approval rating at Rotten Tomatoes), then you might think: Vote him a Razzie!

5. Have a good script. This is the corollary to the "Jack and Jill" theory. John Malkovich is wonderful in "Being John Malkovich" because Charlie Kaufman's screenplay lets him play a distinct character who just happens to share the star's name. (And, yes, because Malkovich is usually pretty wonderful in everything.) Also, if the script's especially clever, as "Being John Malovich"'s is, then it also allows Charlie Sheen to shine by simply being Charlie Sheen — or at least, what we think of as Charlie Sheen. (Refer back to Rule No. 2.)

6. Don't ever yell at Gene Kelly. You remember Gene Kelly? "Singin' in the Rain?" "An American in Paris?" Yes, that Gene Kelly, the song-and-dance legend. If Mr. Kelly has for some unknown reason taken a supporting role opposite you (as you) in your action movie, do not — repeat — do not dress down Mr. Kelly's character in the opening scenes. Especially if you can't act. At. All. It just feels disrespectful. We're looking at you, Evel ("Viva Knievel") Knievel.

7. Remember. No matter how great you are, playing your great self in a movie is one of the hardest things you'll ever do. When Howard Stern signed on to play Howard Stern in his autobiographical "Private Parts," he showed nerves of steel. What if he was as stiff as the mighty and heroic Jackie Robinson in "The Jackie Robinson Story?" What if he was as unconvincing as the all-powerful Muhammad Ali in "The Greatest?" Could he still lay claim to the title of the King of All Media? As it turned out, yes, he could, because unlike those other nonactors turned actors, Stern had screen presence, and it allowed him to do a very convincing turn as the world’s most polarizing radio personality.

Watch 'This is the End' Cast Discuss Self Indulgence with Yahoo! Movies: