You're probably aware of the poor reputation that South Africa has with regards to safety. Violence, rape, carjacking, armed robbery, labour disputes that descend into mass violence and the plethora of private security companies don't exactly paint a rosy picture. Even though crime primarily affects South Africans, especially those who live in poor neighbourhoods, should it be a reason for tourists to avoid the country? The answer is no, not at all: violence is largely confined to the townships and certain parts of the bigger cities. Carefully choose where to go, check things out in advance and keep your wits about you in certain situations.
No exaggeration: crime rates in South African cities are one of the highest in the world. The black communities intownships live in extreme poverty with little or no social or moral support, due to decades of apartheid rule and the ensuing break down of traditional structures. That said, crime and violence are largely confined to the slums and ghettos. In short: know where you're going, check places out in advance and don't blindly wander around. Some areas must be avoided, even when in a car, as carjacking and attacks do occur. Avoid at all costs the downtown areas of Cape Town, Hillbrow and Johannesburg.
If you stick to wealthier, central areas, be warned that bag snatching, violent robberies and car theft are far more commonplace than in UK cities. To keep safe, you should take certain precautions. Choose secure parking areas rather than parking in the street and do not leave anything in your parked car. Leave the glove box open to show there's nothing valuable inside. Don't dress like an obvious tourist, keep your belongings close and make them as inconspicuous as possible.
Robberies are common at night; do not go out alone or walk around isolated areas (beaches, parks). Take extra care in Johannesburg and use taxis rather than getting around on foot.
In rural South Africa, however, crime is relatively low.
Infection-wise, South Africa is one of the safest destinations in Africa , as it's so far from the tropical regions. Vaccination requirements are the same as for European countries. Malaria is only a problem in the northeast, where you'll find the big safari parks including the Kruger - talk to your GP about getting some malaria pills. If you're in this part of the country, use an insect repellent and wear ankle length boots (or longer), as well as long trousers to avoid the risk of tick bites.
Once you're out of the big cities, avoid drinking tap water, which may be contaminated. AIDS is a big problem in South Africa and you must take all precautions necessary.