Are you and your partner chasing a serial killer? Make sure you are the protagonist, not the sidekick.
Unless, of course, he’s played by Anthony Perkins.
Unless you’re Obi Wan Kenobi, in which case you keep on giving advice even after you’ve turned into a slight breeze.
Never be the guy who has the information or skills that would solve everything. Because then you have to die in order for there to be a story.
's why when I saw the first Transformers film, once the main Army guy started talking about “holding his baby girl for the first time” I immediately thought “well, he’s dead.” Probably deliberate that he didn’t get offed.
cue all the snobs chiming in about how they didn’t see Transformers
Being in a dangerous situation, especially a fight and not having any name.
I did like how they winked at this I the newest movie. It is such a well know element of TOS that they had to put it in and they did.
In a bad fantasy story you might meet some grey-bearded, half-senile, half-crippled old man who turns up out of nowhere. And he seems to know more than he’s letting on. Yeah, he’s god. Or at the very least, some sort of angel or powerful being. And at the end of the day, he’ll have some lame, unconvincing excuse as to why he couldn’t intervene directly, rendering most of the story pointless.
So true. I read enough mysteries that I’ve gotten rather tired of this one. The person will usually say “I can’t tell you over the phone”, but there’s almost never any clear reason why they couldn’t. When this person turns up dead I always think “If you’d just said ‘Mr. Smith is the killer!’ when you had the chance, you might be alive now.”
I just wanted to point out the OP username/subject combo.
If you fall in love with either half of the Official Couple and you aren’t the other half, you will die – usually heroically.
You’re the only black guy.
Some shark movie with LL Cool J in it played with this trope by making the black guy live through a ton of impossible scenarios while everyone else died. Of course, he wasn’t the only black guy–Samuel L. Jackson was in the movie for about five minutes before dying, as the full-of-hubris scientist who was sure that engineering giant intelligent sharks would be just fine (see also, Jurassic Park).
“Are we ready to leave? Let me go back in the house/office/basement/attic to get something/check something out.” Cue ominous music.
Thunderstorm? Lights go out? Get a flashlight or light a candle and instead of sitting tight, get up and go down in the basement or up in the attic. Cue ominous music.
The gay guy is probably gonna get it too.
Obviously they can’t say over the phone, since if the killer is listening in, then the killer would know who the killer is.
Being called Disposable Hero would be a pretty hefty clue. 
“They killed my woman” is a pathetically common motivator. The wife/girlfriend of the Action Hero is lucky if she makes it into the story at all.
Bryce Courtenay has a habit of introducing nice young women into his books only to have them violently killed as motivation for the guys to do something. In Lethal Weapon the wife was already dead before the movie started & the Girlfriend in LW2 was wiped out after only one night of lurve.
Also, don’t be the dad in a cowboy film - and definitely don’t let your gunslinger son call you “Paw”.
Displaying any type of cowardice. Run away from the T-Rex and hide in an outhouse? T-Rex eats the outhouse. Hit the emergency door locks to save yourself, but leave your companions behind? You just locked yourself in with xenomorphs. Leave Indy to fend for himself? You’re not making it out of that cave alive. Saying “Are you crazy, I’m not going in there!” and then actually not going in there? Dead in the next five minutes
Pre-1970 or so: Being implicitly gay in a drama. (Inspired a memorable montage of death scenes in the documentary ‘The Celluloid Closet.’)
Any non-cleric who can quote the Bible verbatim.