It depends on how much you are prepared to invest. If you are looking at fast returns on an investment of over 10 lakhs, then restaurant or hotel would be a great choice.
But if you are considering making more money with a low investment in the range of 10,000 to 30,000 then try Stock or Commodity trading is the best option. There are people earning 100% or more returns on investment of 20k to 50k by trading in stocks and commodities. I am a professional trader as well and I'm from Ashok Nagar, Chennai.