Please suggest a good Study plan for FMS Exam.

Decide, if you want to study yourself or join an institute.
In order to make it there, you must go through each and every topic, even the one you feel are not at all important. Because, you never know what would be asked in an exam.
You would need to make a time table and strictly follow it.
Prepare notes- they help a lot in revising.
Once you have fairly gone through all the topics, practice every topic and make notes of it.
Take regular breaks, keep yourself hydrated and listen to music/go for a walk to rejuvenate.
As a part of revision, solve sample question papers and remember your weak areas.