Don’t bring too much! When packing, I make a pile then eliminate, and I always discard any packaging at home rather than carrying trash into areas where it could pose a problem. I also consider the locals and what they need in their remote high-altitude world where weather and environment are challenging.
My pack always contains adequate clothing for fast-changing conditions. I also carry hard candy to ward off the coughing that leads to high-altitude pulmonary edema–enough candy to share with porters who do double duty carrying huge loads. I do not distribute candy (or pens) randomly in villages, a practice which can cultivate begging and worse, a riot if you run out before everyone receives something.
Pens and candy are not what villagers need. Clothing, hats, gloves and socks help them survive and perform physically-demanding jobs. Water bottles that tolerate high temperatures are another thing I leave behind because they allow locals to have and carry their own supply of water purified by boiling. Whatever keep everyone well can ensure the success of any trip.
The extreme light at high altitude and on snow can cause temporary blindness, as in snow blindness, or lead to long-term damage. For the past twenty years I’ve given high-quality sun glasses to village elders and porters, guides and animal herders. They are always appreciated.