comfortable shoes for walking, hat, sunglasses, a jacket or fleece are all essential.
Toiletries and Medical Supplies: Sunscreen, mosquito repellent and toilet paper are all a must.
Photo Equipment: I always travel with my Minolta SLR camera with 2 lenses (1x 35/80 and 1x 75/300 zoom), a two times converter, a polariser for both lenses, a spare battery and 10 spare rolls of 400 asa film (36) with 1 loaded into the camera.
Luggage and bags:
Bring at least one small bag / backpack etc. that is easy to carry a few items in. This will hold your camera and spare clothing during the game drives. Remember SMALL: there will be other people in the game drive vehicle with you. You want something you can hold in your lap if you need to.
Clothing/Shoes/Weather Gear: COMFORTABLE! Even the wealthy movie star tourists that used to stay in the Chobe Game Lodge in the park used to dress for the outdoors.
Game drives happen no matter if it rains or not, so bring something to shed the rain. Thunderstorms come quickly here.
Photo Equipment: At least two cameras - one as a backup. This is particularly important if you have a digital that is slow to save photos. You might miss a key wildlife event if you are waiting for your camera to save the photo.
Telephoto equipment: I suggest a zoom lens so that you can get a variety of distances rather than fixed lens length - you never know how close the animals will be.
High speed film or a digital camera that does good in low light conditions without a flash: some good wildlife sightings are in the cool of morning or evening, when there isn't much light.
Camping/Beach/Outdoor Gear: Flashlihgt, especially one of the Light Emitting Diode (LED) crank or shake powered flashlights: even if you are staying in the luxury of the Chobe Game Lodge, electrical power failures do happen. I suggest the LED flashlight because in my case it seemed to attract FAR fewer insects than any of the other types of light, and therefore used it in my room on a regular basis with the lights turned off.
You will want to take this with you even during the day. You never know when you may have to stop at a "long drop" pit toilet facility that has no lighting in it. These can be very dark when the door gets closed.