There are a few things you need to remember in preparing yourself to achieve a high score on this test. You need to improve your vocabulary and GRE tests your awareness on a wide range of vocabulary which is not normally not used in a day to day conversation. So you need at least 6 months preparation on word list. You must use flash cards to remember the meaning of these words.
Also one must brush up the basic concepts of maths that you have read in 10th standard basic numbers, algebra, trigonometry, geometry, probability, ven diagrams,vectors, parabolas, etc.
Analytical writing ability is a another area that poses challenge to several students especially the engineering students who are weak in English.You need to put in one time here understanding how to write an argument: to do this you must understand the structure of an argument and then how to break the argument into and then take it.Analysis of an issue is the second part of the question : to do well you need to understand the difference between an argument and an issue and then learn how to meaningfully analyse an issue at hand. You must have a critical bent of mind combined with your ability to express your thoughts in good sentence structures that are error free apart from displaying your ability to use a range of vocabulary.This is a separate section and has a good weight age on your verbal score.
Practice Practice and Practice.