Socks: Pack enough socks inner and outer socks (2 pairs of woolen and 2 pairs of cotton/ nylon)
Hiking Boot: Goretex or water proof well used (or friendly to your feet)
Sun Hat: for sunny days. A design which cover neck (hat with neck gaiter) can be good you like or find.
Warm insulating cap of wool, fleece or pile are essential for cold weather, high pass, summiting mountain.
Need 1-2 bandanas and a Buff for protecting neck, head, and face also good for protecting from dust.
Sunglasses: Very important to secure your eyes. Ultraviolet ray protection sunglasses also called polarized.
Upper and lower body Clothing: Gore Tex jacket and pant useful for protecting heat inside keeping cool air out and protecting from cold breeze and rain if happened. That’s your outer layer. As mid layer you should have Fleece jacket or light jacket. Inner pant is recommended for lower body. Also a pair (or two pair) of hiking pants and other necessary inner wear i.e. under wears as you need and prefer. Few t-shirts. Long sleeve shirt 1 or 2 for day time hiking. One warm dawn jacket for cold weather, high passes, base camps. One rain parka.
Hands: A pair of warm gloves. An extra pair simple light glove (as an extra).
Pack (Day pack) : To carry water bottle, camera, map, snacks, first aid, few extra clothing, you need a day pack about 30 liter capacity.
Big Duffel : This one you will give away for porter to carry. This will be where you put your sleeping bag, other clothing and extra things. If two person share the duffel you can bring one big one enough space for both persons equipment and cloths. If you have big rucksac bag that can be alternative of duffel bag.
Water bottle : Camel-pack (piped water pack) or regular water bottle of BPA free plastic or metal. For drinking water treatment, you can bring purification system either tablets or UV system called Steripen.
Sleeping bag: Very important, it’s always better to buy one at home rather than to buy in Kathmandu. Somehow, if you don’t have one or you need the sleeping bag only for one trek then you can rent it in Kathmandu.
Flash Light / Head lamp: With a set of extra batteries
Personal First Aid Kit: (Insect repellent, Moleskin, Diomax, Aspirin, Cipro, vitamins, basic wound care and personal medications if any (for high altitude, diarrhea and cold, etc.)
Pocket Knife (optional) always put in check in bag for the flights you take.
Sunscreen and lip protection
Snack supply of chocolate, power bar, etc in reasonable amount. These you can also buy on the trail.
Toiletries – such as brush, toothpaste, Towel, shaving kit, Hand sanitizer, mask, etc.
Walking Stick – Optional
Camera, Phone, Battery Bank, Reading / writing materials, As per your interest
Due to the limitations of weight while flying in small aircrafts in mountain areas, it is recommended to keep the equipment as light as possible but do not miss the necessary items you feel needed. The list is an idea, you can adjust as per the need and also as per the length and type of trip you are taking part.