Most first time safari travelers pack for a trip they are not taking. Bright colors, heavy boots and a suitcase built for a week in the city all add weight without adding comfort.
Stick to neutral, lightweight clothing that can be layered. Mornings on the Northern Circuit start cold, afternoons get warm fast. A good pair of comfortable closed shoes matters more than a rugged hiking boot, since most of your day is spent seated in a vehicle.
Bring less than you think you need. Most lodges offer laundry service, and a lighter bag makes every transfer easier.