Hi I did this tour in Sept 2011 although it has changed a bit since then. It is really fantastic and I loved South Africa. I had never been on safari before and it was the most wonderful experience and the scenery in SA is out of this world!
My main tips are: see you doctor/practice nurse at least two months before you go to get whatever jabs you need. You will also need malaria tablets for Kruger - Malarone are usually prescribed and these are easy to take with minimal side effects. Make sure you take them after a meal with a good fat content to aid them being absorbed. You will also need to find an insect repellent with 50% DEET to avoid being bitten by mossies (Boots do it) - although they weren't a big problem on my tour. Put on sun screen first and then when it has dried (about 15/20 mins later) put on DEET on your arms and legs (especially on your lower legs and ankles). Be careful not to get it on your clothes or watch/camera etc as it will take the surface off!
As regards other matters, drink only bottled water and use it for washing your teeth as well. I had no tummy troubles in SA at all. Bring a memory card for your camera with plenty of space and if you don't have a camera with a decent zoom consider getting one with at least 20x as the animals and birds might not be close by!
That's all I can think of for the moment, any questions ask away!
Best wishes,
Bob