RULE #1: USE THEM SPARINGLY.
Comparisons draw attention to themselves, like a single red tulip in a sea of yellow ones. They take the reader out of the scene for a moment, while you describe something that isn’t in it, like you’re pushing them out of the story. They require more thought than normal descriptions, as they ask the reader to think about the comparison, like an essay question in the middle of a multiple choice test. They make the image stand out, give it importance, a badge of honor of sorts.
Use too many comparisons and they become tedious.
Elevating every single description is like ending each sentence with an exclamation point. Eventually, the reader decides no one could possibly shout this much, and starts ignoring them.
For these reasons, you should only use metaphorical language when you really want to make an image stand out. Save them for important moments.
RULE #2: USE COMPARISONS THAT FIT INTO THE WORLD OF YOUR STORY.
If you’re writing from the point of view of a character who’s only ever lived in a desert, having that character say, “her look was as cold as snow” doesn’t make much sense. That character isn’t likely to have experienced snow, so it wouldn’t be a reference point to them. They’d be more likely to compare the look to a “moonless desert night” or something along those lines.
Using a comparison that ties to the character’s history or the setting of the story also do work to build the world of the story. It gives you a chance to show the reader exactly what your character’s reference points are, and builds the story’s world. If your reader doesn’t know that desert nights can get cold, this comparison informs both the things its describing: the other character’s look andthe desert at night.
Here’s a metaphor from The Hitchhiker’s Guide to the Galaxy:
If you took a couple of David Bowies and stuck one of the David Bowies on the top of the other David Bowie, then attached another David Bowie to the end of each of the arms of the upper of the first two David Bowies and wrapped the whole business up in a dirty beach robe you would then have something which didn’t exactly look like John Watson, but which those who knew him would find hauntingly familiar.
He was tall and he was gangled.
This is a bizarre comparison, but it’s also a bizarre story. What’s more, David Bowie is known for his persona “Ziggy Stardust” and songs like “Space Oddity.” Bringing him up in a book about a man from Earth traversing the galaxy makes sense. What’s more it increases both of those aspects of the story: its ties to space and its bizarre-ness. The comparison unifies the story and the language being used to tell the story.
Using comparisons that fit into the world ensures that everything is working to help tell the story you want to tell.
RULE #3: MATCH THE TONE TO THE THING BEING DESCRIBED.
Or, match it to the way you want the thing being described to come across. It has to match what you want the reader to feel about the thing being described.
Here’s an example from mental floss’s “18 metaphors & analogies found in actual student papers” (although I think it’s actually from a bad metaphor writing contest):
She had a deep, throaty, genuine laugh, like that sound a dog makes just
before it throws up.
You’re not imagining a laugh right now, are you? You’re imagining a dog throwing up. Whoever this girl is, you’re going to make sure never to tell a joke in front of her.
This is not getting the right point across.
Remember the David Bowies? Remember how the comparison was fun and bizarre, just like the tone of the book is fun and bizarre?
This is not David Bowies stacked on top of one another.
It’s not enough for a comparison to be accurate. It has to bring about the same emotions as the thing it’s describing.
If this is being told from the point of view of a character who hates the laughing character and we’re supposed to hate her and her laugh. It actually does work, but from the use of the word “genuine,” I don’t think this is the case.
Make sure you always pay attention to the tone of the comparison.
RULE #4: KEEP THEM SIMPLE.
Don’t use a comparison that requires too much thought on the reader’s part. You never want anyone sparing even a moment on the question: “but how is x like y?”
Here’s another example from that Mental Floss list:
Long separated by cruel fate, the star-crossed lovers raced across the
grassy field toward each other like two freight trains, one having left
Cleveland at 6:36 p.m. traveling at 55 mph, the other from Topeka at
4:19 p.m. at a speed of 35 mph.
Again, this is a humorous example. It’s supposed to be bad, but many writers have made mistakes like it. They choose two images that don’t have enough in common for the reader to make an easy and obvious comparison between the two. Sometimes, the writer subconsciously acknowledges this, and expands the comparison to a paragraph, detailing the ways the two things are alike.
If you find yourself doing this, take a step back and ask yourself if this is really the best comparison to be using. The best comparisons are the simple ones. All the world’s a stage. Conscience is a man’s compass. Books are the mirrors of the soul.
What about that David Bowie quote, you ask? Douglas Adams broke this rule, but he broke it purposefully to get that bizarre quality to the language. He still avoids reader confusion, the reason for this rule, by bringing the comparison back to its point at the end: “he was tall and he was gangled.”
RULE #5: AVOID CLICHES.
The best comparisons are fresh ones. No one wants to hear that she had “skin as white as snow” and lips “as red as roses” anymore. The slight understanding it brings to the description isn’t worth the reader’s groans when they realize you just made them read that again.
A cliche is a waste of space on the page. It’s not going to be the memorable line you want it to be. It’s not going to awe the reader.
Good similes in metaphors require some creative thinking.
In the vein of rosy lips and snow-colored skin, here’s a fun example from Harry Potter and the Chamber of Secrets. It’s the poem that Ginny wrote for Harry on Valentine’s Day:
His eyes are as green as a fresh pickled toad,
His hair is as dark as a blackboard.
I wish he was mine, he’s really divine,
The hero who conquered the Dark Lord.
These aren’t comparisons you’re like to have come across before and their originality comes from rules #2 and #3. Rowling needed comparisons that fit in Ginny’s frame of reference. She also needed comparisons that were humorously bad, as they’re being recited by a grumpy creature dressed in a diaper, who is sitting on Harry’s ankles, forcing him to listen.
As a witch at school, blackboards and fresh pickled toads fit Ginny’s frame of reference. Neither are particularly known for being nice to look at, so they fit the tone, too.
Using her character, setting, and tone, using, in other words, her story, Rowling was able to create similes that are unique and memorable.
It’s the same thing Adams did with his Bowie analogy.
If you, too, use your story to inform your language, writing new and wonderful similes and metaphors should be just as simple.