Here is information on trekking in Indian Himalayas:- The Himalayas are foremost among the world's trekking destinations, and many routes are extremely challenging.
Trekking alone is extremely risky. It's best to find others to go with you, including an experienced, reputable guide (who may also do all the cooking). There are many trekking companies who can organize all the details for you.
If you are planning a trek, get yourself in the best physical condition possible before you start out. If you have a history of heart or circulatory problems, don't neglect to consult your doctor before planning a trip to high altitudes.
Make sure that someone knows your itinerary and who you are trekking with. Before setting out, get the best maps possible and the most detailed information on your route and the surrounding area. It's hard to get decent maps in India. Much better maps are available overseas, so try to get them before you come. If possible, bring a GPS as well. While it might seem like a great idea to bring a satellite phone, don't even think of bringing one without declaring it, or you could get arrested on suspicion of spying.
Always carry cold-weather gear even in summer, and more supplies than you expect to need. Even in the middle of summer, temperatures can suddenly plunge to freezing at high altitudes, especially at night.
Symptoms of Acute Mountain Sickness (AMS) usually develop during the first 24 hours at a high altitude, but they can take as long as two or three weeks to appear. Milder symptoms include dizziness, headache, lethargy, loss of appetite and difficulty sleeping. Severe symptoms include mental confusion, irrational behavior, breathlessness, vomiting, dry cough, drowsiness, lack of coordination, lack of balance, and severe headache.
If you start feeling sick, don't try to conceal it from your companions or to pretend that it's not as bad as it is. Many people do so for all sorts of foolish reasons. Your life is much more important than some deadline or concern about what people might think. Anyway, no intelligent person is going to think that you are weak because you get altitude sickness. After all, many of the strongest and most intrepid adventurers on the planet have suffered from it. If you deal with AMS in a timely manner, it's not a big problem. If you don't, it can even be fatal.
While it is not possible to prevent altitude sickness altogether, there is no reason why anyone should die of it, since the onset is relatively slow and the progression of the disease is predictable. The real dangers are where one is either trapped in a situation where it is impossible to descend, or else forced to keep moving by people who are determined to push on at all costs. The best prevention for severe altitude sickness is simply to refrain from going higher until all moderate symptoms are gone. Above 10,000 feet or so, it is recommended to increase your altitude by no more than 1,000 feet a day, with a rest day after every 3,000 feet of elevation gained. Adding some extra days for your trek will allow you time to rest in case of need. If you show symptoms of even moderate altitude sickness, wait to go any higher until they subside. If your symptoms continue to get worse, immediately descend to a lower altitude.
Altitude sickness is not much of an issue if you are only crossing a high pass and then descending again to an altitude that is not significantly higher than the one where you spent the previous night, because the onset takes several hours.
In addition to concern for your health, do give some attention to the environment. There are many parts of the Himalayas that are still quite pristine, so if you go trekking, please do your part to keep them that way and carry out everything you might have brought along that is not biodegradable. If you use toilet paper, bury it. Generally be sensitive about the environment. Don't cut trees for firewood or any other purpose. And refrain from polluting streams and lakes with detergent, human waste, etc.