Here's a tip for visual thinkers: cast your story with old time movie stars.
The movie stars iconic faces, if linked in your mind, will keep them distinct, and may help your memory with keeping names distinct.
Failing that, name your characters after the characters in the movies or even the movie stars.
Granted, in might be hard to justify having characters in ancient Mesopotamia running around with names like "Clark" and "Rita" and "Garbo," but...
anyone under the age of 30 won't know what you're doing.
