I think simply using the term "black" makes it clear and doesn't confuse the reader. Do people generally think of characters as white unless it's specified?
I find with white people, unless they have black hair, people will automatically assume by saying they have brown, blond, or red hair, that they are white. But even saying they have black hair isn't enough because both black and white people have black hair.
JK Rowling in Harry Potter and the Sorcerer's Stone wrote this description of Dean Thomas during the Sorting Ceremony. "a Black boy even taller than Ron." I'm confused why they capitalized the word black though since it's a descriptor. Why would that be capitalized?
Another way I think which helps tell the reader if a character is black is by what their name is. There seem to be names which are unique amongst people who are black.
I find "African American" to be an interesting term because I would guess most black Americans were born here and their families have lived here a long time. Thus they're American. What if every American used their ancestory to say who they are, because unless you are Native American (Indian) you can trace your roots to some other country. Would we call people English-American, Scottish-American, Welsh-American, German-American, Russian-American, Chinese-American, Asian-American, Brazilian-American, etc...? Although to be honest, most of us could probably trace our ancestory back to several countries so it would be a rather long title. Like saying you're English-German-Russian-French-American or something.
Enough with my rambling. One question though. If you say that your character has fair skin, does fair refer to the color or feel of the skin?