India is on two different levels always. Internal and external. Urban and rural. Formal and free. Business and tourist. Always on two levels.

Most customs are divided between the traditional and urban settings. Customs in urban settings are more relaxed, except those dealing with religion. In a more traditional setting, customs play an important role. As an outsider, you will mostly always be forgiven, but if you were to explore and observe the interactions of the people of the soil, and mirror their actions (and heed these handy tips) it will surely earn you some goodwill wherever you go.

Let's visit India as a tourist. In this way, you will come in contact with more of India than you imagined.

Greetings

India's most exported word is “Namaste.” Taken literally, it means "I bow to you". It is done by joining both palms in front of you and under your chin. With a smile, it is both welcome and thank you, and a sea of emotions in between. It is the best form of greeting, which knows not any religious or geographical borders.
Men shake hands. Men and women do not.
Most people know the three most important words in English....Apart from those, “Yes” “Please” “Thank You” and “No” are used widely enough.
“Ji” pronounced “Gee” is a suffixed term of respect. Common usage includes “Haan-Ji” meaning “Yes” “Nahin-Ji” meaning “No.”
Thank you can be said as “Dhan-ya-vaad” or “Shuk-riya”

Dressing/Attire

Casual attire for Indian women varies. Normal casual attire is never revealing, and women prefer to dress modestly.
Tourists should be aware of the sensibilities of the Indian people and not wear clothes that reveal too much skin, specially while visiting places of religious significance including graves and mausoleums.
It is customary for women to cover their head when entering any religious place. In a Sikh temple like the Golden Temple in Amritsar, both men and women, Indian or foreigners have to cover their head.

Religions

India plays host to seven major religions of the world. As a secular nation, all individuals are free to profess any or all religions of their choice. However, a few customs and rules regarding religions must be borne in mind, to avoid any unintentional gaffes and blunders. Hinduism is the major religion in India, with Islam coming in second. While Indian Muslims are more liberal than their counterparts in Iran and Saudi Arabia, certain rules still apply. Buddhists, Jains, Sikhs, Christians, Parsis and Jews make up the remaining fabric of India.

Hindus do not eat beef. Most Hindus are vegetarian.
The right hand is in fact the “right” hand. Everything should be given and taken with the right hand, specially money, gifts and food.
Slippers and footwear are generally left at the doorstep before entering the house.
Each house will generally have a designated prayer room. No footwear allowed.
Muslims do not eat pork.
Muslims do not drink alcohol.
Certain places of worship are exclusively for believers of the religion, while others are open to all. Churches are free to all. Most Hindu temples are as well. Certain shrines to Muslim holy men, like the Ajmer-Sharif Dargah, Nizamuddin Dargah are open to all faiths. Zoroastrian temples are off-limits to non-Parsis.
Sikhs are people who wear turbans and have beards. It is mandated by their religion that they carry a weapon, to prevent injustice to innocent people. Do not be alarmed. They are the most jovial people of all.
It is not common for Indian women to smoke. You will cause a few heads to turn if you are a smoking woman. Not to worry. They'll get used to it. So will you.
NO SMOKING in any religious place. Sikhs are disallowed from smoking and consider it offensive if you smoke in front of them.

Socialising/Dining

Indians love to party, though levels and extremities vary. We are very friendly people, warm and hospitable. Following practices apply largely to events at homes of your hosts, not while out at a club or restaurant.

Indian food does not go well with alcohol. Normal practice is to drink to hearts content before attacking the dinner table. In this process, dinner might end up being served late. Be prepared.
Wines are not the drink of choice for Indians. We like our drinks to go straight to the head and get the job done. Rum and whiskey are the most consumed.
Country liquor must be tried. It is different in almost every state. We'd recommend not trying it alone though. It is extremely potent.
Food is enjoyed best when eaten with your hands. Cutlery will be provided at your option.
Washing hands before sitting down to eat is advisable.
It is not unusual to be served by the lady of the house. She will take pride in explaining the cuisine.
Wasting food is not acceptable. Serve or ask to be served a little. You may go for seconds or even sevenths, but try to avoid wasting.
Save space for desserts. “Sweetening the mouth” of the guest is essential to a good meal.
Coffee or tea is not served at the end of a meal.
The table may be cleared soon after the meal is done. This is not unusual. Nor a hint.

Weddings/Occasions and Gifts

Most occasions have a religious basis to them or ill incorporate an invocation to the divine. Common occasions are naming ceremonies, weddings, significant birthdays (60th & 80th), new commercial ventures, new purchases and house warmings.
Weddings are hugely religious ceremonies. Traditional weddings last over a few days, with different ceremonies and rites to be followed. If ever you are offered an opportunity to participate in an Indian wedding, DO NOT LET IT PASS!!
Gifts are always welcome.
Lakshmi is the Goddess of Wealth. Money is never given in “round figures.” It is never Rs. 1000. It is Rs. 1001. The additional one signifies that the Goddess of Wealth will never “stop” coming to a person's home. Similarly, wallets and purses are never gifted without putting one or two rupees into them beforehand.
Red, green and yellow are auspicious colours.
When invited to a person's home for the first time, a good gift is a box of sweets or fruits.
As a businesses traveller, you will see a very different face of India – vibrant, confident and ready to meet the world.

Men and women shake hands. Men wear business suits. Some women wear western formal wear, most dress in Indian formal wear. It is a matter of comfort.

Businesses Meetings and Networking

Indians love to do business in a personal manner.
Successful deals are struck over a cup of tea in the canteen as well as in boardrooms. Indians like to know the people they intend to do business with. Relationships are built upon mutual trust and respect.
In general, Indians prefer to have long-standing personal relationships prior to doing business. It may be a good idea to go through a third party introduction. This gives you immediate credibility.
Wait to be invited before using someone's first name without a title.
Use the right hand to give and receive business cards.
Always present your business card so the recipient may read the card as it is handed to them.

Negotiating and Deal-making

Deal-making is a slow process.
Decisions are made by the person with the most authority
Indians love a bargain. And we love to bargain. Most Indians expect concessions in both price and terms. It is acceptable to expect concessions in return for those you grant.
Never appear overly legalistic during negotiations. In general, Indians do not trust the legal system and someone's word is sufficient to reach an agreement.
So, you are now set to visit India, ready to don the hat of a tourist or the cuff-links of savoir faire businessman.

Namaste, and welcome