My wife and I lived in Sandon ZA, a suburb of Johannesburg, for a good part of 2004; traveling back and forth to the US. My wife went through Cape Town also. We found that paying attention to everything around you is the best practice.
We found the cheapest option was to look very closely in Rosebank mall or the mall at Sandon at what the locals were wearing and then go to Woolworths department store and buy some inexpensive versions. Look at shoes & socks as well as slacks and blouses/shirts. A quick wash will take the "new" look out of them and if you don't have anything that comes close in your luggage, you will have some new duds. We would also recommend buying a "track phone" at the Votaphone store in the mall, as soon as you can. Buy the cheapest one you can find. It may be the best investment you will ever make.
AND, if you rent a car - they drive on left side of the road from the right side of the car!!! Be wary of getting off the main roads. What looks like a shortcut will put you in the middle of nowhere; which is somewhere you do not want to be. Two for instance: On the road from the airport to Sandon or Pretoria you go around the loop like most American cities. What looks like a shortcut through SOWETO is a ghetto that makes East St. Louis look hospitible. People have taken that shortcut; never to be heard from again. DO NOT TAKE A SHORTCUT! Stay on the loop until you get to your exit. The off ramps to Pretoria are especially dangerous; so much so that there are warning signs at the bottom of off ramp warning you to not stop. Judge your distance and blow through the stop sign.
On the positive side, I loved it so much that I have been trying to get my wife to move there ever since we retired. There is crime everywhere and the US is not exempted. We live just outside Little Rock and even a small city like Little Rock has a murder or two a night. It is just how difficult the world is in this 21st Century. We loved the Rosebank flee market on Sundays. Rivers Church is a wonderful place to worship if you are looking for a Christian church. We also spent some time in Swaziland, driving there from Johannesburg. We currently support a Bible mission to Swaziland.
George & Sue Hilliker