You'll probably want a high quality down bag like this one from Mountain equipment shop
A fiberfill bag will be warm enough except in late December and January Insulated jacket
It's cold up there; be sure you have a warm insulated jacket
If you're not going high, a lighter jacket will be enough. You won't need one in April and May
Fleece is light and stays warm even when wet.
Try a windproof version
If you are traveling with porters, you'll need a strong, waterproof duffel bag for your gear.
If you have a porter you'll need only a daypack
If you're carrying all your gear, you'll need a larger pack
Don't forget this. Forget all the complicated stuff, buy a good Nalgene bottle that does not leak and you can take it to bed as a hot water bottle.
Flashlight or Torch
A small hand-carry flashlight is a good choice. Be sure to put a string on it so you don't drop it.
Though many people prefer a headlamp - which is easier to use when you are reading and bed (and you don't risk dropping it into the toilet!).
High top shoes provide ankle support
But many people prefer lighter, low-top shoes.
Boots are a better choice if you are going to high altitudes
Here is the women's version
Gore Tex Parka
It's expensive, but Gore Tex keeps you dry Women's Jacket
Less expensive rainwear
Or use a poncho, which is cooler in hot weather
Sunglasses or goggles
Get a pair with side shields like these
Shorts, Shirts and hats
Preferably with scissors
Sandals for Camp wear
A single walking stick
Or a pair of poles
Or an inexpensive GPS
Other equipments :-
Comfortable trekking clothes, sufficient underwear to wash and change, raincoat, umbrella.
For the Night
warm night dress, torch, toilet-paper, thermo matrices, head pillow, oropax. (toilet papers can buy in the most of the famous trekking region)
Safety / Health
Money belt, spare money, credit card, copies of important documents, medicine box, crèmes and tapes, antibiotics, antihistamines and antidiarrhoea. Sun protection, hat, lip fat stick, electrolyte minerals.
Writing and painting material, candies, torches, crèmes, tobaccos, Polaroid photos, medicines, second hand clothes and shoes.
Walkman or disc man, batteries, books, enough money in small amounts, Go for the Trekking Information.