Hi ujji0074u.
As you are aware, there are a variety of ways to prepare for the GMAT, and which would be best for you depends on your learning style, you time frame, and how much you want to spend.
Which would be best for you also depends on where your skills are currently in relation to what they would have to be in order for you to hit your score goal.
Accordingly, to get a better sense of what you need to do in order to hit your score goal, you should think about what goal might make sense for you and take an official GMAT mock test from here
https://www.mba.com/exam-prep/gmat-offi ... and-2-free to see how your skills are currently. Before you take that mock test, you should familiarize yourself with the GMAT and do some practice questions of each type, so that when you take the test you are actually doing a reasonable job of answering questions rather than figuring out how the basics of how to go about answering the questions as you take that test.
Once you have a sense of how much you will need to do in order to hit your score goal, you will be in a better position to determine what approach to use.
I can say that many people find that using a self-study course works well for preparing for the GMAT. When using a self-study course, you work at your own pace, and, at the same time, such a course gives you structure, instruction, and many practice questions. To choose a self study course, you could check out the course reviews here.
https://gmatclub.com/reviews/gmat_courses/