Hie,

You must first know the complete syllabus and exam pattern for the IIT JAM exam. Then make a proper timetable which you can follow regularly. Divide your time equally for all topics and subtopics. You must also practice the question papers or sample papers or the mock test to have better hands on. You can also follow the link below to know all the latest update regarding preparation - https://university.careers360.com/articles/how-prepare-for-jam

All the Best