Well, I used free material on:
and I did many practice exams on:
GraduateTestPrep.com // Online GRE Preparation
also, I used kaplan GRE General Study Book
These really helped me.
GraduateTestPrep.com // Online GRE Preparation featured new upto date GRE questions in an online computer adaptive test format. By doing their tests, I felt more confident and I am very happy with my final scores!
Good luck everybody,
Lara