BITSAT information.

can someone plz tell me if it is necessary to take a test series for BITSAT and AIEEE or buy a book or in simple words, do any kind of other preparation for the exams?
or will the preparation for IIT be enough for the exam?
:Just wanted to know as there are some institutes holding test series separately for the two exams and I was confused as to whether I should take them or not..

Thanks