Tipping 

You don't need to tip taxi and autorickshaw drivers for a normal ride, however if you have hired the vehicle for the day a tip is expected.  Hotel, airport and train station porters should be tipped approximately Rs10/bag.  If a service charge is not included, tip guides and drivers approximately Rs100 per day or 10 percent where appropriate. In restaurants, if the service was good, tip anything between Rs 50 to Rs. 200 or approx 5-10 % of the bill. Depending on the category of the hotel, and the bill amount. But a Rs. 200 (about $ 5) tip is considered reasonable even at most upscale places. 

Etiquette

Indians dress conservatively, arms and legs largely covered.  If you must go around in beach wear, shorts and T-shirts etc no-one will say anything but you can be sure that your appearance will not be appreciated. Dress according to the weather, if its very hot wear light clothing., but if you are a lady, very revealing attire will attract unwanted attention.

When entering temples, mosques or buildings of religious importance always check what dress attire is required.  In most cases you will be required to cover your head, take off your shoes and be dressed conservatively.

Be respectful towards seniors.

Your left hand is used for wiping your bottom. If you are not using a fork and spoon, don't eat with it, handle food with it or pass anybody anything with it.  Again, nobody will say anything but you can bet they'll disapprove inwardly. 

Show respect for local cultural practices. Steeped in cultural and religious diversity as India is, people are generally very tolerant and open-minded while dealing with foreigners and will go out of their way to help you. Return the favour by showing respect for local beliefs and traditions.