Walking boots, strong trousers or gaiters, (gardening) gloves to protect you hands from enormous stingy nettle, waterproof jacket, long-sleeved shirt, warm jacket for the evenings
Toiletries and Medical Supplies: Mosquito repellant, anti-malaria tablets
Photo Equipment: Fast film, tripod/mono pod
So, you may think "Oh, its Africa. In a jungle. I'll just bring shorts." Well, my friend, think again. It was truly cold in the mornings, as you are at elevation. But, that isn't even the main reason. That would be little devil plants called "stinging nettles". They are aptly named, as the sting slightly in isolation, but 20 in concert make you want to kill yourself. I had pants and a long sleeve, but they managed to poke right through, and I made the mistake of having no gloves. At one point, I truly wanted to scream, as the cumulative effect was extremely obnoxious. Thankfully, it wears off in about 5 minutes, so by the time you reach the gorillas and settle down, the burning is long gone.
Toiletries and Medical Supplies: Perhaps a pain killer or two might help blunt the pain.
Photo Equipment: You know that movie "Gorillas in the Mist"? Yeah, its appropriately named. So, know that lighting will be poor. The better your iso and the higher your shutter speed the better.