Flat comfortable shoes should be worn. A jacket, sweater or fleece which can be easily removed during the flight as the sun warms up the air is ideal. Sun hats & sun glasses are also recommended.
If you have a choice of lenses carry both the wide angle & telephoto. Faster film is vital as take off is at sunrise. Carry enough film & a camera bag to put in your equipment when landing. Video cameras are great & binoculars invaluable for game watching. Hot Air Balloons are very photogenic.