First thing to get in place is a proper licence :
There are enough players who have a licence and are not using it. Rather than pursuing a license of your own start with partnering with someone. License as such has become a commodity and entities not having the required license have been partnering with banks/ppi holders to launch services . To name a few partnerships
So if you have a good idea over and above of what is being offered in the market go ahead and skim the list of PPI holders and convince them ( esp the ones who have not been able to capitalise) to work with you - Prepaid Payment Instruments in India. Getting in touch with banks in another option but they won't entertain a relatively new player .
On a side note a lot of them have already surendered their licenses ( Beam Money, Done Card Utility and OSS Payment solutions ) and before others do the same please get in touch with them and impress them with your proposition .
Once this is in place , iron out the use cases you want to hit the market with . Typical use cases are recharge and bill payments but only these services are not going to help you out and probably you need to innovate here to stand out in this crowded space. One you are clear with this get the right partners onboard and get the technology in place.
Next comes user acquisition and getting people to use your application. Iterate and keep on adding new use cases to get the engagement going.