Frankly there's no Formula to crack ca final..u must remember how did u prepare for ca pe2 n get cleared ur groups...every body has different grasping power,memory,analaytical skill,focus level.etc.......if u already completed the course at least once....4 months can be well utilised to to make concepts more clear n revising syllabus........work hard n hope for the best....confidence is the biggest thing......if u utilise 4 mnths thorougly it is sufficient if u can not even 4 years is less.....................i'm sure no body can tell u the best strategy because there is no formula.......don't emphasis on authors emaphasis on concepts.....