Hi kopal96,
There are lots of general guidelines about GMAT prep / study plans but the key to tailoring it to your requirements is to know the following:
1) Your target schools and target score
2) How much time you have to take the test
3) Whether you have taken a diagnostic test and how it went
In general, I would suggest a few things:
It's important to fully cover all the core material once by going through the Official Guide or
Manhattan Prep Guide. Along the way it's important to take practice test to 1) get yourself accustomed to the format and experience of taking the test and 2) identify areas that need improvement
The other thing I would suggest is keeping a balance between focusing on studying content and improving your in-test processes. Remember that content knowledge is the foundation of your ability to succeed on the test, but how you tackling problems in both quant and verbal is equally critical.
The reason is this: the GMAT is a test of executive reasoning (not Math or English). What the test writers and ultimately the MBA schools are looking for your ability to succeed in the high reasoning environment of business school. For that reason, the test reward smart processes for tacking questions. For example, in quant, a lot of the traps in harder questions are beaten by strongly following the 4 key stages of solving a quant problem:
1) Capture and preprocessing the prompt, answer choices and (in the case of Data Sufficiency) the statements.
2) Visualization of a text based problem into a visual format (tables, number lines etc).
3) Setups of equations / calculations that will lead to the final answer
4) Execution of the final calculation including things like estimation, rapid number testing etc.
There is much more detail to all this but I wanted get you thinking about focusing on process as much as content right from the beginning. My experience is that balance can cut prep time from scratch by 50% (ie. shaving off months) and if you're doing a retake, it can reduce prep time to weeks instead of months.
Hope this helps. Let me know if you'd like any specific personalized advice -- I'm happy to connect on a call.