Having done a few safaris now, I feel as though I can give some advice on the "do's" and "dont's"! Firstly clothing - do NOT wear the following colours when you are on a game drive - Blue, black (both attract tsetse flies), white (gets filthy) and absolutely no bright colours! Best colours to wear are khaki, brown, tan etc. i.e. muted colours that blend with the bush. No heavyweight jeans (take too long to dry). Pack a couple of long sleeved shirts that can be rolled up (Craghoppers have insect repellent in the cloth), zipped-off trousers are good, and you may need a fleece for the early morning game drives.
Other things you will need - a good pair of binoculars, a camera with the best lens you can afford (I use 300mm), lots of memory cards, spare batteries (you quite often can't buy these at the lodges), chargers, wide-brimmed hat, sunglasses, insect repellent, sun cream. If you have long journeys, an ipod or similar is useful. Only drink bottled water & avoid ice in drinks. Don't forget your malaria pills and any jabs you may need.
Hope this helps - enjoy!