So if you are writing an essay about Crooks' strengths and weaknesses, sometimes you have to look at a strength (or weakness) and make it the opposite especially if you have found many of one.
As you look at his color, you could call that a weakness. However, tha weakness has caused his to inevitably develop a strength. Crooks is probably more literate than the rest of the guys that go through there. This is because he reads all the time, he has to in order to keep occupied, no one will befriend him. See how that works? Because no one lives with him and he stays in the same place, he has quite a collection of books too:
And he had books, too; a tattered dictionary and a mauled copy of the California civil code for 1905.There were battered magazines and a few dirty books on a special shelf over his bunk.
This variety of literature demonstrates a man who could think and enjoy himself. Most of the other guys could not do either.
Crooks can read between the lines too. I would say he is intuitive. He knows when people want him around and when they don't. Most of the time they don't want him around. He realizes that his thoughts don't matter to other people even though he probably is much more intelligent than the other guys for reasons we have already discussed:
If I say something, why it's just a nigger saying it.
See how he realizes where he stands. Most people don't get it, they don't know that others judge them. Crooks is wise.
Hope that helps!