"How do I write a character of color without using stereotypes?"
I get this question often and it is legitimate. Creating characters is not easy. Creating characters that belong to a different racial group than you are can be down-right difficult. You don't want to rely on stereotypes to describe them that can be offensive, harmful, or cliche. In response to that apprehension I often see authors avoid it, they take the easy way out and you don't describe them at all, but is that what's best?
When I'm sensitivity reading I often see basic and rudimentary physical descriptions of primary or secondary black characters:
she had chocolate brown skin and big, round eyes
By itself, there is nothing wrong with this description. It's not necessary for every character to have a full, detailed description. It's only problematic when this description is compared to the description of a primary or secondary white character:
his brown hair was in a military crew cut and he had icy blue eyes and pale skin
The white character is described more richly and the reader can form a picture in their mind, the black character's description is incomplete in comparison, therefore, the reader is forced to fill in the gaps.
This is what I tell my authors if they want deep character descriptions:
Find a picture of a real person who looks similar to your character (you made need more than one person) and use that as your guide.
Free write: Write out every single detail of the description. Whatever is in your mind just write it out.
Edit: Trim it down so it is more concise and note the words that you feel are stereotypical. Use a thesaurus to exchange those words for others.
Here's where the hard work comes in:
Remember that real person you were basing your character description on? Imagine reading your description to that person aloud. Try it. Pretend like that person is in front of you and read your description. If you wouldn't feel comfortable saying it to that person's face than it shouldn't be on your page.
Finally, be creative and if it doesn't feel right keep editing and ask for help.
Additional resources for writing character descriptions:
Writing With Color: Description Guide
10 Tips for Writing Physical Descriptions of Your Characters