As a tourist, it's not as bad as it sounds. South Africa has a LOT of violent crime, but tourists aren't usually the victims. Home invasions, farm attacks and a lot of violent crimes in poor areas. When it comes to tourists it's mostly like any other big city in the world. Don't drive after dark, and don't wander alone around the city at night. Other than that, just use common sense and you'll be fine.
South Africa does however have a few things that at least most eurpeans aren't used to. 1) Car guards. When you park someone will look after your car for a couple of rands. At shopping centers they usually have uniforms, in a city street it could be homeless kids. 2) You don't fill petrol yourself, and give a few rands to the attendant and more if they clean you windshield. 3) Small talk. You have to exchange a fair bit of pleasantries before getting to the point. Weird for a scandinavian, but I think it's quite nice. 4) They call traffic lights "robot" 5) If someone passes you on the road, they expect you to drive on the shoulder to let them pass. They say thank you by flashing their emergency lights after passing.
When it comes to tourist scams there are just a few, but they're not exclusive to SA. 1) Someone asks to help you when you're using the ATM. 2) At the airport there are a lot of pirate taxi drivers. Go to the taxi rank, or arrange transport with your hotel. I've ended up in pirate taxi twice, but had no hassle. 3) There are porters at the airport, but they have vests usually. Pay them a few rands if you let them bring your luggage in.
Haven't really experienced overcharging except once in a taxi, his meter kept bumping up every time he braked, haha. But it was such a small amount that we just didn't give him tips.
Places to avoid, city centers at night and townships by yourself. Other than that, just listen to the locals and your hotel tells you. It really isn't that different to London or New York etc.
Safari packing list: Layered clothing (thin wool sweater or fleece will help a lot at night/early morning), scarf, beanie, camera, memory cards, extra battery, sunglasses, sun lotion, mosquito spray, mosquito net (depending on where you're going and if you're afraid of bugs)binoculars. What you DON'T need is khaki clothing, you do not have to dress up like Livingstone to go on safari. Just bring normal comfortable clothing like sweat pants/jeans, hoodie, running shoes or other comfortable shoes.
What not to eat? There's so much yummy food, that I say, try it all. Almost. My personal don'ts are walkie talkies (chicken feet and beaks) and smilies (half a sheep's head). Tap water is safe, but I avoid it because different bacteria tends to give me an upset stomach. You should try impala, springbok, kudu, ostrich, cape maley curries, seafood, bobotie, sticky toffee pudding, don pedros, malva pudding, biltong, amarula, boerwoers, pap, sheeba.