Regarding traditions, customs, what is good and what is bad behaviour in India?

I am from Costa Rica and there is a slight possibility that I may be going to India by the end of the year. I want to make sure that when I get there I wont be doing anything improper or insulting, as it has happened to any uninstructed tourist outside his own country. I would like to avoid such embarasing and potentially offensive moments, by learning what I should make shure to do and not to do, in India I.E. words I should avoid, table manners, behaviour in a residence, at a temple or on the street, etc.