Hi Mo,

• Go to DG website and get the RPSL list.
• Make your own list of companies in your area.e.g Mumbai,channai, Delhi.etc.
• Sponsorship exams will be conducted by companies for interested candidates, the information about the exam dates can be obtained from the companies website.
• If there are no exam dates mentioned in the company website, then you may mail the company requesting them to offer you sponsorship.
• Once the company agrees to give you a interview date, then you are on your way.
• Make sure you check the company websites time to time for sponsorship examination dates.
• Companies normally prefer candidates having one or more family members in the Merchant Navy. It is not a compulsion though, if the candidate is capable and has the right attitude required for a job on-board then he will get through.
• Approach with positive attitude, speak fluently and clearly.
• Most of the company Like MSC, OCS Nortrans, Essar,MSI,ABS, Pentagon conduct interviews in October- December every year.For GME and send their cadets to MERI Mumbai for 1 year PGDME(GME) course.
• Great eastern,Anglo eastern, IMS Goa,Sci these are the good institute you can also apply there. 

Refer the below link for the list of RPSL list i.e, Companies offering Sponsorships.

http://www.dgshipping.gov.in/Content/RPSAgencies.aspx