The image I had of India came from documentaries, Bollywood films and some knowledge on Hinduism. So I went on an adventure, without buying a guide, although I regretted that a little bit later in the stay, without really knowing what to expect.
Here are some must-haves to help you prepare for your stay:
On my arrival the first shock was the way of driving in India. Indians drive on the left and it is the only logic respected, and again, "Chaotic" is a weak word. All types of vehicles were on roads, ranging from Rickshaws to elephants!
These vehicles will be your preferred means of transportation. Practical and cheap (for those who know how to negotiate), you just have to make a sign at the side of the road to make them come. The trip is sometimes an obstacle course. It must be ensured that the driver knows the address well (which is not always the case). Then comes the famous negotiation. There is indeed no fixed price in advance.
I have never seen in 2 months an Indian getting upset. However, these are not the opportunities that are missing. Patience is very often required because the conception of time and planning is very different from ours.
Another important aspect is the fact that the Indians almost never say "no", probably for fear of showing that they are not able to perform the task. Religion is also an important aspect of Indian culture. I have often been asked what is my own religion, which is absolutely not taboo in India.