Driving in hills is certainly different than routine city driving.
You can use auto mode on the ascend. But you must use manual mode on descent and keep the car in smaller gears.
Use auto mode on expressway until Lower Topa, or even upto Jhika gali, but from there onward I would recommend using manual mode. Use lower gears to keep the car in high rev and slow down through engine, not brakes (use brakes sparingly).
Descent from Nathia gali to Abbottabad is pretty steep and if you feel that you've been unable to slow down the car enough through engine and have used brakes often then take few stops on the way so that brakes can cool down.
Apart from being careful to not overspeed on the descent, the only other thing you have to be careful of is overtaking. Never ever overtake the vehicle in front when there is a turn close by. Only overtake when you can clearly see the empty straight road ahead.
Btw do keep some candies with you. Travelling in those areas can be nauseating and keeping a candy in mouth after some time will help dispel that feeling 
