In mosques and temples it is obligatory to take off your shoes. It may also be customary to take off your footwear while entering into homes, follow other people's lead.
It is disrespectful to touch or point at people with your feet. If done accidentally, you will find that Indians will make a quick gesture of apology that involves touching the offended person with the right hand, and then moving the hand to the chest and to the eyes. It is a good idea mmm to emulate that.
Books and written material are treated with respect, as they are considered the concrete form of the Hindu Goddess of Learning, Saraswati. So a book should not be touched with the feet and if accidentally touched, the same gesture of apology as is made to people (see above) is performed.
The same goes with currency, or anything associated with wealth (especially gold). They are treated as Goddess Lakshmi (of Wealth) in human form, and ought not to be disrespected.
Food and water - Hindus consider followers of other religions to
be impure but not actually untouchable(Only in certain parts of
North India). Ritually, this ranks most foreigners below everyone
except untouchables who permform polluting tasks like tanning,
butchering or 'sweeping' (cleaning up filth, attending in
bathrooms, etc.), as well as a number of seemingly innocuous
crafts including tailors, musicians, metalworkers and cobblers.
Foreign visitors should understand that their touch is considered to pollute food and drink for any higher caste person, probably meaning it must be discarded.
Touch an earthenware container and it will need to be destroyed. Enter a kitchen and the entire room will need a complicated purification ritual. Not everyone still follows these rules, and shunning untouchables is illegal. Nevertheless traditional rules are still followed in most of the countryside, and even in cities.
You may make friends with an emancipated urbanite, only to discover that they live in a traditional extended family that is not so relaxed about these matters. It is always best to try to follow as many of these rules as possible, until explicitly told what is or is not necessary.
