I'm planning to start one as well. I will note your answers and From what I have learned about this industry is that the location is an important factor for attracting your customers. Good quality or High quality of the food served is a must. The service ought to be the best in the industry. And ambience is yet another thing people come for to enjoy again and again.
As said earlier availability of goods*(veggies or meat or fish or any perishables) on time and their storage must be given due care. Proximity to market helps.
A chef who should be dedicated in his/her cooking is a must.
Being Exotic can do some magic for a while.
Decoration, interiors, music, lightings,cutlery,
furniture are everything minutest should be given attention to details.
Understand and observe people and their desire for food and the kind of service they expect from you.
Explore a lot before you indulge.
Good luck!