Always try and pack as little as possible as you will regret carrying a heavy bag/backpack, especially if you are going to have to walk some distances. Don't be tempted to bring too many clothes, I guarantee that half of them you won't wear.
What you pack all depends on whether you are going on a two week holiday, long journey spanning across several countries, the time of year you are travelling and how you are travelling.
If you are going on an organised safari you may be limited to baggage size you can take on your safari vehicle - so check first with your operator.
If you are travelling independently it is advisable that you take a backpack (Rucksack) rather than a suitcase - you may have to walk distances to find accommodation etc. and a backpack will make life a lot easier.
Top loader backpacks can be a real pain when you want something quickly that has wormed its way to the bottom, fully opening backpacks (with a zip going all round) are much better for accessing the contents of your bag and when fully open can be used as storage, no need to unpack!
Make sure snaggy straps can be stowed in a pouch on the bag (especially when going in the baggage hold of aircraft) and the lining has a degree of waterproofing or comes with a cover, maybe have a large plastic bag available so that you can place the rucksack in it if required. On bus roofs bags can get wet when it rains.
Watch out for metal zips, I have had bags become impossible to open/close after a few weeks at the beach, the salt will cause the zip to corrode and stick (smear vaseline on the zip to free it up). Plastic zips are fine as long as they actually have teeth (bigger the better), the loop type plastic zips are prone to coming apart under pressure. Broken zips are the number one reason for ditching a bag, give them a good try before you buy.
Make sure that it is the right size or a good strong make and sits comfortably on your back.
Having a small shoulder bag for your more valuable items means you can keep them with you.
Pocket knife - Swiss Army is the best
Small Sewing kit
Twisted elasticated clothesline (no need for pegs)
Electrical adapter (if needed)
Camera, film and extra batteries
Small battery operated alarm clock
Ziplock Plastic bags for electronics and film Lighter
Small torch (Flashlight) black outs are frequent in most of Africa
Mosquito net impregnated with permethrin
Water Bottle - in case bottled water is not available
The rule is take as little as possible - it all depends on which area of Africa you are travelling around and the climate at time of travel
1 x Long-sleeved shirts/blouse,
2 x Light long trousers will help protect you against the sun and insect bites.
2 x Skirts/Dresses
3 x T/Shirts
2 x shorts
1 x Swimsuit
1 x small towel (Sarong is better)
1 x Hat that shades your neck
3 x pairs Socks
Cotton Underwear and socks
1 x good pair of well broken in Walking boots
1 x Plimsolls/Sandals or flipflops
Toiletries: toothpaste, soap, shampoo - although you can purchase these items along the way
Pkt. baby wipes or wet wipes (if travelling in remote regions).
Insect repellent containing DEET
Some kind of pain killer
Band aid and bandage
Immodium and other Anti-diarrhoea medicine
Iodine tablets and water filters to purify water if bottled water is not available.
Prescription medications: make sure you have enough to last during your trip, as well as a copy of the prescription(s).
If you wear glasses or contact lenses, you should have with you a spare pair of glasses or enough lenses and cleaning solutions to last your trip. Also carry with you a copy of your prescription.
If you take oral contraception you should have enough supplies to last your trip.
Bearing in mind the widespread AIDS epidemic, syringes & needles (in more remote areas these may be in short supply) and condoms or femidoms are necessary items.