Dear Ashish,
Field of SAP is open market, opportunity driven field. There is no defined prerequisite. Even SAP certification is not mandatory.
But on the basis of my own experience, some of prerequisite for SAP career are
Domain Experience
Patience
Financial Backup
Perseverance quality, and on top of all
Live project experience.
Without which one can not get through in the field of SAP. 
Regards
Chirag