The whole point of parodies and satire is that it pokes fun at a genre or specific story. Usually, they do this by overexaggerating the source material or pointing out some particular flaw.
To properly do this, though, you need to know the source material inside and out. You need to know how the genre works, properly identify its flaws and poke fun at them without sounding bitter or mean-spirited toward the person who wrote it.
The parody itself also needs to be entertaining in its own right. What's the point of criticizing a more successful franchise if you as the author can't even get a few chuckles out of the audience?
- Know the source material
- Mock the tired tropes they use
- Be respectful
- Don't take yourself too seriously
Let's pick some genres and brainstorm ideas for writing parodies of them:
First, think of some common horror movie tropes. Probably a bunch of jump scares. A monster. A house in the woods. A killer in a mask. Protagonists with little common sense.
Now how could we make fun of that? Ramp up the ridiculousness as much as you'd like, and turn the tropes on their head.
The serial killer is actually a cereal killer. He only wanted your Cheerios.
The monster's made of spaghetti. You should have finished your pasta.
Tell the story from the monster's perspective. Now it's a horror story about a monster running from a group of teens, or a whole group of monsters running from a single kid.
Common tropes in this genre include things like having your character be the Chosen One bound by fate to defeat the Dark Lord who can only be defeated by some ancient magic item that probably has a piece of his soul tied to it. There's probably a prophecy of some type binding the character's soul. Also, your character will probably be trained by a wise old wizard.
I know this is the plot of Lord of the Rings, but you'd be amazed how many times people use this exact formula.
If your story is urban fantasy, it'll probably be very similar except they started out as a normal person and are then thrown into this unknown world where they are probably the Chosen One or at least special in some way, like being a wizard or a half-elf or part demon or demigod. Etc.
Personally, the Chosen One trope is one of my least favorites. My proposal for a funny satire would be the following.
"You're the Chosen One, Felicia," Greybeard the wizard said.
"Really? Who chose me?"
"You were chosen by the goddess of Pufferfish because you're 1/16th elf on your mother's side, born on a leap year under a full moon, and had your soul bargained away to a gnome on the year of the Crocodile."
"Yes, but what am I chosen for?"
"Chosen to steal a plate of spaghetti from Dark Lord Smellsalot's table."
"Why? Because he's evil?"
"No, because I'm hungry."