Geographically India is as big as Europe, but in the range of its diversity, there is no match to it. Since many centuries India has been a multi-religious, multi-ethnic and multi cultural society. Hindus, Muslims, Sikhs, Christians, Jews Zoroastrians, Jains, Buddhist, tribals and many more have found home in this subcontinent.
As a consequence, India is a garden which has a myriad of customs and rituals which form a part of India's allure. While it will take many lifetimes to understand the reason, the significance and the art of these customs and I doubt if there is someone even in India who can confidently claim that she knows all, still there are some established ground rules that can take you far on the path of Indian customs, once understood.
As India is predominantly a Hindu country, the most common form of greeting is namaste. In the southern parts of India it is pronounced as "Namaskaram". In the State of Tamil Nadu, people use "Vanakkam". This is a non-contact traditional and customary method of greeting each other, irrespective of gender, age, or social background. Handshakes or embraces are used for intimate or close relationships. The Meaning of "Namaste"
Namaskar is performed by joining the palms together (fingers pointing up words) and simultaneously bowing the head. With respect to elders or authority figures, the head is bowed down considerably.
This whole ritual sales in words and deeds that I acknowledge and respect the divinity that resides in you as well is in me. The position of the joint palms in reference to the body is important and indicates the relationship between the two.
It is not necessary to use the word namaste and the gesture together always. Gesture is more important.
There are some scholars who explain that this gesture evolved due to need of its times when people greeting each other, needed to display or disclose that they are not armed.
This is a popular method of greeting and can be used pan India with all communities as a foreigner to this country. However, amongst Indians. It is the predominant form of greeting amongst the Hindus, though Muslims use it as well when greeting Hindus.
Muslims within their community use "Assalam-e-Alekum" as the starting greet, which is returned by "Walekum-Assalam". These utterances are accompanied by a sweeping gesture on the right hand from the side of the body to either the heart of forehead. It means "Peace be upon you"
With the non-Muslims, while this is used fair bit, even more popular is the use of the word "Adaab" accompanied by the gesture. Apparently this was developed to make it easier for the non-Muslims were probably challenged by the pronunciation of Assalam-e-Alekum.
Within close relationships or on the occasion of the Id, embrace of three short hugs with the heads crossing each other left, right, left is popular. The Sikhs greet by the call Sat Sri Akal, meaning "The truth is the timeless".
Amongst the Tibetans, the call is "Tashi Delek" approximately meaning "May everything we well". In the north eastern part of India, in the state of Meghalaya, expect to hear the call "Khublei" meaning "May God bless you".
Embracing and hugging.
Generally, an urban phenomenon, the exceptions are as mentioned above. Hence not recommended in the initial phase of your relationship. Ofcourse if it is time of cultural festivals of India, then do it.
Touching feet - Pranam
Often you'll spot younger people touching the feet of the elders in the communities that are not of Semitic origin. This is widespread and is highly expected in those communities that practice it. Hindus, Sikhs, Buddhists and Jains are imbibed with this custom.
When the young one the feet of the elder, the elder blesses the young one by placing his hand on to the head of the feet toucher. Mostly you will see the short Pranam, but there is a Pranam, which involves full prostration on the ground in front of the revered one. Generally reserved for spiritual heads/gurus.
Namaste serves the dual purpose of greeting, as well as saying goodbye. In the Muslims, it is "Khuda Hafiz" or "Allah Hafiz". With the Sikhs, it is "Rab Rakha". All of these terms mean that God shall take care of you.
Bengalis prefer using "Aashchhi", little bit similar to the French "Au Revoir" - I'll be back. French meaning is - see you again.
In Kerala, it is "Sukhaayirku" or "take care"