Interactive Brokers is hands down the best brokerage in terms of commissions and a one of its kind in giving a retail investor exposure to global markets ( NASDAQ SYMBOL : IBKR ). However customer service is not too good and it is meant for pros.I am not sure of the legal aspects of trading commodities overseas from India, however you probably can get into commodity ETFs without direct exposure.
Disclaimer: I am not affliated with Interactive Brokers, I am a customer of Interactive Brokers.