how to start a restaurant business in a metropolis like kolkata?

I am Subrata Boral and I work in an Industrial manufacturing company. We are looking for a diversification in to the restaurant business in kolkata in some prime location in and around park street area. We want to set up a speciality restaurant. I want to know what are the things I will have to first take care of ? Can you suggest any organisation from whom I can seek some help in this regard. Please suggest the best possible way out.