India is a part of global village. While it is a country and almost a nation, it is a place of diversity in all respect. The crucial problem is greeting on first meeting. How do we greet each other. While there are many methods but there is thread of emotion behind the gestures. The gesture varies from the clasping of hands in traditional Namaste or Namaskar to plain or simple nod.
The popular gesture is plain and simple nodding of head with short bowing like gesture. This is presently the universal greeting if there no further interaction is intended.

Next is handshake in English way. This is popular in all business meets. Shop keepers would not expect every customer to come and shake hand. It will do with all but at some places, rural or traditional women may not shake hands with a stranger. Some women will not like it in cosmopolitan cities as well.
Namaste or Namaskar (see picture) is a formal expression used mostly to give respect to an elder or otherwise respectable person. Namaste is generally not a person to person greeting any more except in interior places away from major towns. The response could be a Namaste or a nod or a ‘kind of pat/short caress on the back’ depending upon the nature of greeting but for a foreigner, response with Namaste will do fine. Please note that Namaste is welcome and also a good bye and often signify end of meeting. More like SHALOM. Any how it is formal greeting just like hand shake.
Touching of feet is only a gesture by bowing in front of another but no one actually touches the feet any more. This is a traditional way of greeting elders and only elders. It is also called ‘PARI PENNA’ in Punjabi and ‘CHARAN SPARSH’ in Hindi which is also used in written communication or phone. It means ‘I am touching your feet.’ It is formal but very popular in social events where younger greet the elders. If some one does it, it is an offer of deep respect. Respond by touching his/her back and lifting the person and embracing in a hug as a sign of affection. Do not try to touch feet in return. Do not try to do it at all as people will be baffled at such gesture by a foreigner.
Hugging is another common gesture. A person hugging is either feeling affectionate or has met after a long time and are close to each other.
Hello and Hi do well with people of contemporary age. No physical touch required. Adding a nod and smile makes it better and natural.
Smile is important. If a person does not smile, it means that he/she does not mean it at all and is simply getting over it. Girls with braces on teeth are not excepted or exempted from smile.
Good Morning, afternoon, evening do all right with English speaking people but is formal.
French peck on the cheek is popular in all parties of rich and ‘who is who’ socialites, theater artists and show business. Do if every one is doing. Do not do with females unless other male members are doing. This is a niche greeting which can be a purely socialite greeting or affectionate.
A kiss of forehead is also a response from elders to young or not so young children.
There are few Hindu greetings called ‘Ram Ram’, Hariom and Jai Srikrishna, Jai Shivaji. Response to these greetings is to repeat the same. Exactly or may add the universal Indian suffix ‘Ji’.
There are Muslim greetings. Aadab in which right arm is raised to touch forehead but may stop short. The response for this greeting could be a sharp nod with smile or simply raise your arm and imitate. Namaskar/Namaste would also do.
Salam is quite like Aadab but is no more a Muslim greeting. In it’s universal development the palm of hand can be out side but hand definitely and swiftly touches forehead. This is greeting usually made to known passerby. It may be verbose with any thing like ‘How are you’ or ‘Ram Ram’ or any curt statement like ‘enjoying the holiday’. It is similar to waving of hand from a moving vehicle to a an acquaintance seen on red light but had no time to stop. Do not imitate this unless you are in a movement.
Apart from above description, there is always a matter of personal preference. Do not reach out to shake hand too often. A lot of people do not like touching may respond with Namaste.
So what to do while in India? Watch the body language and learn. It may sound complex but it is not. Greeting tells how two persons know each other. Unless sure stick to nodding once with grin like smile.
Welcome to India. After Deepawali next month, it is best time to visit India. North will be pleasant while south will be less hot (may be warm). All the best.