Particularly the Gauten/Johannesburg area? When I finally move there, I'll start my "Coli Breh in the Motherland" thread but for now, all my brehs who've lived or work that, drop some knowledge so I don't end up like Ice Cube's brother in "Dangerous Ground".
I'm from Johannesburg (Joburg, Jozi). AMA.
Where are you going to live? The CBD is a dump so fair warning don't even look at as an option. I've lived in Joburg all my life and only speak English and Afrikaans. Learning Zulu could be advantageous but is not a requirement. English is all you need to get around. Off the top of my head I'd say:
Make sure you can drive stick.
Don't go to Babylon.
Always be courteous.
Don't eat pies from garages. Actually don't eat pies unless it made by a human being you know.
Best places to get woman are varsity towns (Braamfontein, Auckland Park, etc).