1) Aluminium foil- Carry aluminium foil so that you can cover your tiffin in this before you take the food. When I didn't carry foil, I had to clean the entire tiffin in super cold water after I had eaten. If you cover your tiffin in foil, you can simply throw the foil after that without needing to clean the tiffin. This is a great way to stay warm and prevent freezing hands.
2) tying laces- It is a huge problem if your laces keep opening after you've tied them on the trek. However, it is great to tie the double knot lace so that the laces don't open and you don't risk tripping. Also, it will save you time of checking your laces and will give you a lot of more confidence.
3) Porter- Take the porter on your first trek if your bag is heavy or if you are underprepared. It makes your task of trekking a lot more easier. However, taking a porter is not good enough reason to be underprepared.
4) torch for the tent- At night, you may want to enjoy the stars without any artificial light but the tent may get super dark and scary. It is great to carry a torch for the tent so that you don't end up being scared at night. I had to pee at night and I had forgotten the torch, it was really scary and I woke my tent mates up.
5) Always use the sleeping bag comforter lining- If you use the comforter lining, you will surely be 5 degrees warmer than normal.
6) Pee before you sleep- Peeing before you sleep is very important. Waking up at night to pee will not only disturb your sleep but it is very difficult to sleep on the mountains once you have woken up. Always pee before you sleep so that you can be comfortable with nice sleep in the morning. Walking all the way to the bathroom stalls at night is very scary. Do not do it alone even if you wake up. However, I once woke up on the trek to pee and I enjoyed the amazing view of the stars.
7) Eat well before you go to trek and eat alot of rice- Rice has carbohydrates. Most mountain people consume rice to have extra energy to trek. You will be served rice in almost every meal, try to eat as much as you can.
8) Do not consume a lot of maggi- Maggi causes problems on the mountain, you can eat some of it but not too much because the body will have trouble digesting it.
9) Always shut the tent properly before you have slept. The tent has two zips, one for the net, one for the actual opening- I had forgotten to shut the net zip before I slept. It got too cold at night because all the freezing wind had entered our tent. If you don't shut the tent, your tent mates will hate you and you will ruin their sleep. My tent mates were really understanding though because it was my first trek.
10) Always pack some lunch or keep some food with you for the way- It is very natural to feel very hungry on the way sometimes, carry a protein bar which won't take a lot of space and enjoy it among the trees amidst nature. You don't want to trek when you're exhausted.
Extra: If you have any problems, always tell your trek guide otherwise it may get even bigger. Always to stay safe than be sorry.