Before you begin packing, do your research. Read up on the area you are going to and note down temperatures. Plan activities for the day and your end destination.
You will over pack if you don’t follow this simple step. If you coordinate your outfits beforehand, 5 tops and 3 bottoms can make 15 different outfits. Additionally, pack multiple thin layers at all times - this makes adjusting to the outside temperature a lot easier. When picking outfits, selecting wrinkle free and water resistant clothing is the obvious choice, but make sure that the fabric of your outfit breathes, allowing for body temperature adjustment.
Not only should you make sure you have hats, gloves and socks aplenty, but also remember to pack chap-stick, sun-screen, and sunglasses. Cold weather does not leave one immune from the effects of the sun, which can often be stronger when sunlight reflects off the snow.
Make sure you use all the space in your bag efficiently. Roll your outfits, so they take up less space, and make sure the crevices of the bag and your outfits are holding other items, like the sunscreen and lip balm. This will minimize the space you use in your backpack and also ensure a tight and secure bundle.
Make sure you are comfortable with your back-pack. You are going to be wearing it throughout, and it needs to be appropriate for your body frame. If possible, opt for a waterproof bag.
Before you go hiking, it is best to ask locals and any guides about necessary items. Most people would have hiked on the same route and would be able to give you valuable tips regarding it.