The following points could be very useful:
1. Permits are required to visit protected areas in Sikkim and the tour must be organized by Registered Local Travel Agents for such visits. Further, minimum of two persons are required for such permit.
2. Nathula is open from Tuesday to Sunday and closed on Monday.
3. It is recommended to attend at least one folk dance or drama while in Sikkim as it is the true mirror of Sikkimese culture.
4. Plastic items including mineral water bottles in banned in some places of Sikkim.
5. It is advisable to not include too many places into their itinerary. A day or half must be kept free to take rest and to shop or explore the place on your own.
6. It is advised to keep photo copies of important travel documents and identity cards. Pass photos come in really handy.
7. Anti bacterial creams and sun screen lotions must be carried along to avoid the suntan and bacterial infections.
8. Carrying of luggage can be very tricky. While excess baggage is a nightmare, make sure you have few woollen clothes. Clothes, boots, etc. are also available on rent in high altitude areas.
9. Respect culture and traditions of Sikkim. Do not Litter, Do not spit, Do not smoke at public places, Do not urinate at public places. Maintain silence inside the monastery.
10. Don't forget camera with additional batteries/extra storage or a good camera phone.
11. Hilly curvy bumpy roads may cause motion sickness. Don't forget to carry medicines.
12. Momos, dont forget momos!! And local alcohol in case you drink!!
13. Respect Defence Rules. Do not cross lines or click photographs where you are not allowed to.
14. Do not stay at Lake Gurudongmar or Nathula pass for more than an hour. The oxygen levels are real low. Leave Lake Gurudongmar before noon. It gets very windy up there.
15. Cab charges for North Sikkim are higher than the rest of the state. Do not insist on trying your hand on driving. The local drivers are experts.
16. Entry to Lake Gurudongmar has age and health condition restrictions. Ask your travel agent for advice.
17. Since Sikkim lies in the east, it gets dark very early. So it is advisable to start early.
18. Mineral water below 2 litres is banned in Sikkim in order to curb plastic pollution. Drinking water is available in most of Hotels and restaurants. Hence it is advised to carry a reusable water bottle.