A good place to start is to take an official GMAT practice test.
You can download the free software at
https://www.mba.com/the-gmat/download-fr ... n-software
Who know? You may already be at (or above) your target score
After that, you'll need a game plan.
We have a Learning Guide at
https://www.gmatprepnow.com/learning-guide/overview, which provides a road map to follow in your studies.
BTG also has a Study Guide at
https://www.beatthegmat.com/mba/gmat-guide
I hope that helps.
If you have any other questions, feel free to ask.
Cheers,
Brent