Can you please clarify to me the rule regarding adjective order?

Question

I have long, black, curly hair OR
I have long, curly, black hair ???

You can refuse to be tested orally only once. (or You can decide to excuse for not being tested orally only once)
I don't know how to express it.

Answer 1

Both work just fine.
I have long, black, curly hair.
I have long, curly, black hair.
http://grammar.ccc.commnet.edu/grammar/commas.htm See #5.
and
http://grammar.ccc.commnet.edu/grammar/adjectives.htm
Scroll down to The Order of Adjectives...

This is fine:
You can refuse to be tested orally only once.