Together with the GMAT Prep software from mba.com - yes, the two together are sufficient - if you have a clear plan.
There's plenty of material here - but if you need more, you can go to:
https://www.gmatpill.com/gmat-practice-test/This online question bank is free to sign up and use. Paid membership is required for expert video explanations.
As for your study plan:
Start off studying sort of "on-the-side" -- then once you commit to kicking things into high-gear -- then it's nothing but studying. Live, breath, and sleep the GMAT for full entire days. And then rest -- and then go at it again - then rest. Then review - and kickass on the exam.
https://www.gmatpill.com/gmat-practice-t ... study-plan
We also recommend a
"Divide and Conquer" approach first.
That is -
focus on specific sections - like Sentence Correction. Dedicate an entire day - heck, dedicate multiple consecutive days dedicated ONLY to sentence correction.
For example: tomorrow is
"Sentence Correction Day" - and don't move on until you feel you've made a significant improvement and have results to show.
If you operate with that kind of work ethic - and apply that process to RC, RC, PS, DS, etc. -- then you will have individually made good progress in each section.
Then from there, it's about
mixing and matching different verbal and quant questions - just as you would see them on the actual test. So take practice tests to simulate this mental switch between different question types under time pressure.
For practice, we recommend the practice tests from mba.com as was from supplemental resources such as this one from GMAT Pill:
https://www.gmatpill.com/gmat-practice-t ... ctice-testTo learn more about GMAT Pill - read our stories at
https://www.gmatpill.com/testimonials