what books should be preffered for studing GRE exam? what type of subjects, sums,etc are required to study the portion of GRE?

the best book is BARRONS guide. onto quants side, try getting concepts in place. all questions are conceptual. just RS Agarwal practice would suffice. the most difficult part to crack is the verbal ability. i would suggest you to do arun sharma for that.

firstly u need the word list and then there is this book GRE which has completely covered the syllabus of maths as well combined with english requirements.. anyways u would have to take help from some GRE classes because the method of solving maths is totally different and quick which is the necess

Start with BARONS guide to prepare for English.