The longer you're out hiking, the tireder you get, the more your concentration wanes, and the more you risk putting a foot wrong. Unlike a walk in the woods, stumbling, slipping or losing your balance in the mountains can have disastrous consequences, and in the worst case result in a fall.
Leave yourself enough time
To enjoy your trip to the mountains from beginning to end, you should make sure you leave yourself enough time for the descent. Try to avoid a situation where you have to hike back down under time pressure faster than you normally would. In fact on your descent you should deliberately slow down and take more breaks so you have the strength and concentration to place your feet carefully.
The right gait
Your centre of gravity shouldn't be behind your body, especially on a steep descent. Lean forward a little and bend your knees slightly. Pick up your feet high enough to avoid stumbling. To take the strain off your joints, actively slow yourself or use trekking poles.
Planning your route
If possible, take the train or cable car back into the valley or choose an easier route than you took on your ascent. Keep an eye out for fields of old snow. They might have been easy to negotiate on your way up, but they can quickly get very slippery on the way down. If you don't have such a good head for heights or are prone to dizziness you should keep turning around on your descent to make sure you don't have any problems.