Luggage and bags:
To carry your gear you'll need a main pack of approx 70L and a day bag big enough for food and water during game drives. My day bag is only 22L and it was easy big enough for both the Serengeti and Kilimanjaro.
Clothing/Shoes/Weather Gear: As you are at 2500M when camping at Simba A, it will be rather chilly. Make sure that you have plenty of warm clothing with you. Remember that it's very dusty here so what ever you wear on your feet, if the dust can get in it will! Sports shoes (tennis shoes, runners etc) will let the dust in but will be comfortable. I'd recommend that you bring sports sandals if you have them or Jandals (thongs, flip flops) which are also really good for shower & toilet time. A wet and wind proof jacket is handy though during the day in the warmer months it get quite hot! Quick dry tee shirts and shorts will be worn mostly so bring those but remember that if you are using Malaria tabs that make you sun sensitive to cover up with a wide brimmed hat.
Toiletries and Medical Supplies: Always bring extra toilet paper! This is vital to your comfort. Medical supplies will often be part of your tour guides kit if you are doing a tour - if not then you can buy an essential kit before you leave home (bandages, insect repellant 40% deet, sunscreen, anti bacterial cream, runny bottom pills etc)
Photo Equipment: If you are like me then your main concern here is battery life of your digital camera and storage media. I had a small digital camera that used AA batteries so I never had an issue. Others brought very fancy cameras that needed recharging - our truck had a charge board so all good - will pay to check this before you decide! I've seen some good solar charging eqpt for Mobile phones though these can be pricey and doesn't connect to many digital cameras.
Camping/Beach/Outdoor Gear: You'll need to carry a sleeping bag plus tent and ground mat unless these are provided. The addition of a sleeping bag liner will come in handy here to help keep you warm. It also keeps your bag clean given the lack of washing that you may have to cope with.
Miscellaneous: A head torch is very useful as there is normally no lighting at night - unless you have a full moon lol. Also think of things such as a deck of cards and travel diary. Also good to bring is a towel, clothes washing soap and clothes line (aka spare shoe laces). I never travel anywhere without a book or 3 to read either!
Clothing/Shoes/Weather Gear: It should go without saying, but you'll spend a lot of the day sticking your head out of the roof of the landrover in the Ngorongoro crater, and you should make sure to take a good hat and some sunscreen if you don't want your main memory to be of a terrible sunburn. A decent pair of binoculars certainly won't be a waste, and a wildlife guide will certainly clarify what you're looking at much of the time, especially when the animals are unfamiliar.