Wash before every meal. Not only is this a sign of respect, but after hours of trekking along dusty roads, it's a matter of hygiene so carry a water bottle and wet wipes with you at all times. In terms of eating, generally you use your right hand to pick up food, but if you find that too difficult you can employ the 'ole British way of knife and forking it. Your left hand is typically the one to hold your drink or pass food. The rituals of eating are very specific - right down to the amount of digits you use to pull meat off a bone, and this is all dependant by which region you're in. We're confused too. Best plan of attack is to observe, ask and be mindful that in India, dining is a respectful slow process (e.g. they don't drive around with double cheeseburgers hanging from their mouths and call it Lunch). Alcohol is seldom drunk with a traditional meal, but don't fret - a gift of beer or whiskey is appropriate if you know your host enjoys a tipple.
Haggling can be good fun, and the vendors expected it, particularly at outdoor markets but do not go overboard. If a shirt is a dollar, you're doing pretty well to start with; don't push to the point of being a dick. With taxis and rickshaws, negotiate the price with the driver before you start your journey and when it comes time to cough up, there's absolutely zero room for further negotiation - on either side. Often you'll be offered a biscuit and a cup of tea upon entering a shop or home. Accept these guestures graciously (
In the larger cities (Delhi, Bombay, Bangalore) and areas where there are hoards of tourists (Goa, Kerala, Arga), you can generally get away with less conservative clothing but there's virtually no reason to ditch the modesty code entirely. You can keep cool AND covered, so consider heading to India with an empty suitcase - they've got your sorted (and for far less than that garish Camilla kaftan you intended to bring). Ideally, women keep their arms and legs covered at all times, so carry a light shawl with you. For footwear, try sandals as opposed to sneakers (which paints a huge TOURIST sign on your head) and when you get cold, whack some socks under them. Yes folks, we've found a country where socks and sandals are accepted. HOORAY!
IconPark's British India has an amazing concept infusing the grandeur of imperial Britain to the delicious melting pot of India. Take a moment to look at their incredible journey here.