As with all international travel, you'll need a passport and the appropriate visitor's visa. (With the exception of South Africa, Zimbabwe and Botswana, all African nations require visas. These are different from one country to another, so ask your travel agent or safari company how to apply or check your destination country on this U.S. State Department site.) Most African countries do require some inoculations, depending on where you're coming from and where you've traveled most recently. Check with a local travel clinic, which can provide computer printouts of required shots (a yellow fever vaccination is probably on that list) and make sure you get them on time. You'll probably also need malarial prophylactics, so ask your doctor about that, too. Before you go, make sure your personal health insurance is in good order.

Here's a quick list of things you'll need for almost any kind of safari:

Duffle bags -- They're easier to load into cars when moving camp.
Comfortable clothes -- Pack reasonable quantities of cotton shirts, shorts, jeans and light-weight wool socks, a sweater or windbreaker for the evenings, walking shoes and light sandals for camp, a hat and plenty of sun block. Traditional khaki, green and brown "safari outfits," sold everywhere in Africa, are especially good because they allow wearers to blend in with the scenery and because they're cotton, they breathe and can be easily washed and dried.
Cameras -- Experts recommend using a camera with a zoom of 70 to 300 (even higher if you're an avid birdwatcher). Film is very expensive in Africa, so you should bring plenty from home -- some experts say 40 rolls of 36 exposures of ASA 400 is a good rule of thumb. Although some professional photographers prefer to use lower speed film, faster film is good for getting shots of moving animals. A video camera will enable you to film with less light and to pick up the unique sounds of Africa. Most safari companies can recharge your batteries from their vehicles.
Binoculars -- A must for a safari! Any good pair will do.
Water bottle
Flashlight

Remember that each African nation has a different culture, government and currency, so be sure to do your homework before you travel. A couple more essentials for your trip: your sense of humor -- remember, it won't be like home! -- and your respect for Africa's people and wildlife! And before you go, check out some of the Web sites and good books related to Africa and safaris. If you're especially interested in animal behavior, check out The Safari Companion: A Guide to Watching African Mammals, including Hoofed Animals, Carnivores and Primates, by Richard D. Estes with illustrator Daniel Otte (Chelsea Green Publishing, 1999).