You should budget at least 1 month of actual studying and maybe another 1 month of psychological preparation.
Start off with a diagnostic from mba.com and then get a sense of the different questions. See where you problem areas are and if you need any additional help.
You can follow this 1 month study plan:
https://www.gmatpill.com/the-gmat-pill-m ... tudy-plan/The most cost effective way is to focus on the highest quality prep materials from the GMAT makers themselves:
1) GMAT Prep software
2) Official Guide 11th or 12th edition is fine
If you want more practice, you can use OG Verbal review and Quant review books
The GMAT verbal is arguably more important to your score than GMAT quant as described in this article:
https://www.gmatpill.com/the-gmat-pill-m ... -strategy/Of the GMAT verbal sections, SC is the easiest to improve and RC is probably the section that will take the longest time to improve. These
RC videos may help.
Some people recommend reading the NY Times. While that may be beneficial in the long run, it's unlikely that reading NYTimes will actually help boost your score in a few weeks. Focus on keywords in the passage so you know when you should really pay attention and when you can "skim" parts of a paragraph. This is almost an art rather than a science and takes time to develop.
Whatever material you do end up using, make sure you follow these tips:
https://www.gmatpill.com/practice-questi ... mat-study/Hope that helps!