Avoid visiting Kashmir in the extreme north as well as areas in the extreme north east. The rest of India is safe haven for everybody.

The Western practice of a peck on the cheek as a form of greeting a lady or a grown up girl is generally not acceptable in India.

If you are male introduced to a lady or a grown-up girl, don't take the initiative of offering a handshake. If the lady extends her hand, you must reciprocate, but don't be the first to extend your hand.
If you are female and are being introduced to a male: it is up to you - the female - to take the initiative for a handshake. The rule of thumb is: the female extends her hand first, and the male reciprocates.

The namastay is the local form of greeting. It involves the joining of your palms as during prayer in the church. If you find the lady is not extending a handshake, go for the namastay. Even with men, the namastay can be an excellent little PR gimmick! Follow it up with a kaise hai (how are you?) and you have broken the first block of ice if one there was!

Don't trust strangers with money. Trust your hotel, but not people you may bump into on the streets.

If somebody has invited you home for dinner, carry with you a box of sweets or at least a chocolate bar for the kid.

If you are buying from roadside stalls or hawkers bargain you must. Start by offering half the price they ask for and settle for 60 per cent. Don't bargain in proper shops especially those that display "Fixed Price" signs: that will be seen as bad manners.

All foreigners are advised not buy ready-to-eat food from roadside stalls or mobile canteens. Not that they are bad, but your system may not be accustomed to such delicacies. There are plenty of reasonably priced restaurants in all Indian cities and towns. If you are in a place where you can't find a decent restaurant, buy packaged bread and butter and make do.

Drink bottled water. Even many Indians who have lived out of India for a while sometimes suffer stomach upsets on drinking local tap water. If there is no alternative to tap water, ensure it is boiled.

Avoid offers of spiritual salvation and magic remedies from saints, god men and quacks. There may be some spiritually elevated people in India, but there is no way you can distinguish the genuine ones from the crooks. If you are seriously interested in these aspects of India, take help from someone you know or visit one of the respected spiritual organizations in India.

Avoid driving in India unless you have been trained on Indian roads.

Avoid promiscuous sex in India, or take precautions.