A distinctive appearance for each character is perhaps less important in books than it is in movies or graphic novels, but that doesn’t mean your character’s appearance (including what is and isn’t mentioned about it) doesn’t matter. Your characters should spring to life, and part of that is giving them an appearance that makes sense.
Treatment from other characters
Done well, description can indicate character traits or backstory elements, and even be used to further a plot. Does your character resemble a family member? Do they suit the standards for beauty in their society? Is there an indication in their dress of their religion, job or culture? Are they in the majority in their society, or not? How other characters react to or treat them can and should line up with their physical appearance. It’s one of the many ways to make fiction read as ‘true’.
Unless your character is oblivious or of high enough status to be surrounded by flattery, their appearance should affect how they are treated by other characters. Happily, if you’ve written in the effect a character’s appearance has on their life, you’ll have a natural way to describe their appearance. If their culture has traditions or assumptions relating to dress, hair length, the use or lack thereof of cosmetics, skin colour, hair colour etc etc (as most do), it should be simple enough to throw a paragraph or two in about what aspect of a given character’s appearance likely inspires the response they receive from the world at large.
If your piece is written in first person, this may be trickier to do, as internal monologues don’t naturally tend to dwell on known facts. In this case, dialogue may be a better option. Perhaps your character’s parent, child, boss or client comments on their appearance, compliments them, or asks them to alter the way they look in some way.
In a group setting, comparisons can also be very effective. Though again I feel the need to caution against a character spending half a chapter bemoaning the colour of their hair, the fact that their friend has clearer skin than them, or their lack of height. If course, even this technique could be done effectively (perhaps for indicating a character’s immaturity or entitlement); but in general, people don’t sit around thinking about each part of their body and what they’d change. If they do, it’s likely a character trait that will need to continue throughout the book, leading to an important plot point.
Is your character illegitimate, with their appearance a key indicator of that? Does their eye colour indicate a heritage or magical ability that is treated poorly in their society? Is the uniform they habitually wear hated by the people they live amongst?
If a character’s appearance is introduced as a source of angst, it should be used for character growth or development, the same way any other powerful, emotional response would be.
My preferred way of absorbing character descriptions is through subtle hints. If a character looking up to make eye contact with someone else to indicate their comparative shorter height. A character shuffling aside to make room for someone to pass them as a way to indicate either larger size, or cramped quarters. A character smiling to seem less threatening means something about them could otherwise indicate a threat. If your character hides a certain feature/aspect of their appearance, obviously it is something that would change the way they are treated, most likely in a negative fashion. Describing a character (or characters) in this way is a great way to interweave descriptors with character moments, backstory, or world-building elements. It is the most seamless way to integrate character descriptors.
When and how to introduce the physical appearance of your character is up to you, though please try to avoid a character (almost exclusively a woman) critically evaluating herself in a mirror.
Her piercing blue eyes, her curling blonde hair, her milky white skin, her pert breasts, the synchronised groan of a million readers…
Interwoven description isn’t always possible in shorter fiction or for minor characters, and in that case don’t discount the power of simple descriptors. The tall woman, the southern trader, the king’s guard. Just make sure that the descriptor you choose for a character gives the impression you intend. If you want your readers to see a character as sensitive and poetic, describing them only as muscular and imposing will likely lead to confusion. Subverting stereotypes is all well and good, but it takes up space on the page. If you don’t have the words to use up describing your musclebound poet, focus instead on details that do give the impression you want, with the muscular appearance of the character being an afterthought.
Yes, Grak could crush walnuts with his bare hands, but those hands were ink splattered and free of calluses that did not come from a quill. It was rumoured he grew so strong because he had to climb a mountain to reach the duchess’s library, and that he did so three times a day as a young lad to read of the work of the greats…
Changing up the way you introduce a character’s appearance (if you’re giving an indication of multiple characters, say at the beginning of a book) can be a way to make the descriptive process seem less forced. If your story begins with three separate characters looking in the mirror; being complimented or insulted; or having a character exclaim about their resemblance to a family member or historic figure, it will likely become tiresome. But if you spread the descriptive moments out a little and use a different method for each, it can be an effective way to give your readers a way to picture your character without dumping the information all at once.