I have a really hard time picturing characters, both in other people’s stories and in my own. Maybe this is why I don’t mind books made into movies, since I never really had a clear idea of the characters in my head to start with. I’m not sure exactly why this is, but unless I see a picture of the character (like on the cover of the book) I won’t know—and I won’t care—what they look like.
Probably one reason for my apathy toward character’s physical appearances is because so many authors, especially amateur ones, do a really poor job of description. In the first chapter they might mention a character’s ‘long blonde hair’ or ‘deep blue eyes’ and then leave it at that. There’s nothing remarkable about that character. If their blonde hair has no bearing on the story, then I might as well think it was black. If it doesn’t matter that her eyes are blue, why can’t I think they’re brown? In short, if a character’s appearance doesn’t matter, then your description is worthless.
The thing is, though, as much as we try to avoid it: appearance matters. It changes the way people think about the character. It changes the way the character thinks about themselves and about others. This isn’t just a black and white I’m-pretty-so-everyone-loves-me or I’m-ugly-I-want-to-be-someone-else sort of thing. It’s much more complicated than that.I’m short. Most of the time, I’m perfectly fine with that. Sometimes, however, when I’m standing next to some other people who are tall and wearing high heels, and I’m just wearing flats, I feel really small and insignificant. I feel like a little kid. It doesn’t help that I also look young. So, in specific situations, my height and general tiny size, makes me feel somehow unimportant. If you’re writing about a short character, they may have similar feelings. On the flip side, if you have a tall MC, she may feel really self-conscious and shy about towering over everyone.
All of your characters should have some sort of defining characteristic. I’m short and have thick, really annoying brown hair. One of my friends has short, ridiculously curly (but super cute) hair, while another has longer curly hair that looks thick, but it’s really thin when she straightens it. Another friend has freckles on one half of her face and not on the other. My sister has a tiny little bump on one ear that she calls her ‘earring.’
To help your readers picture the characters, give them a defining physical characteristic. This doesn’t need to be anything too weird, just something that the readers will remember. Then don’t forget to figure out what the MC thinks about these features. Does she love her hair, or hate it? Does he still wear glasses because he can’t stand the thought of touching his eyeball to put contacts in? Don’t forget to figure out what other people think about your MC’s looks. I have a friend with huge gorgeous eyes that everyone loves… except her. Perhaps your character’s most beautiful feature is actually the one that she hates?
Physical appearance is something that everyone has to deal with, every day of their lives. What we look like can have a huge impact on how we think, act and talk with others. Don’t be content with giving your MC a generic appearance and then forgetting about it. Let their appearance affect the character’s personality, just as if they were a real person.

