Hi there,
Getting ahead of your GPA is a pretty prudent thing to. There are definitely a few options open to you. Oh, and rocking the GMAT won't hurt
The first is enrolling in a local university to take classes that either remedy red flags on your transcript (e.g. didn't do too well in math, so you take an advanced calc course) or round out your business pre-MBA credentials (e.g. statistics or business math). If you live near a good university this strategy can pay off by giving you in person experience. Not only does it help build your alternative transcript, but you learn more in the process as well just as a factor of being present. If the university has a strong brand, that can help too! If the ones in proximity are not as well regarded, that isn't to say you shouldn't pursue this option but, hey, always nice to have a great name on your secondary transcript, right?
The second option are extension courses offered by well regarded institutions such as UCLA and Berkeley. They offer online courses that are specifically tailored to the pre-MBA student. An MBA curriculum is designed to be fast paced (they don't want you to waste your ~$5,000 a class) and building on knowledge you should, theoretically, already have. If you don't have the foundation, you're going to struggle. For example, if you don't have a solid grasp of statistics, you're not only going to have to take the basic stats course which may not be why you went to bschool, but you're going to struggle in other courses as well. Everything from finance to marketing uses advanced stats and, potentially, regressions. Taking courses that align well with the bschool foundation are what they're looking for. That's where these extensions come to the rescue!
The third option covers solutions such as MBA Math. It gives you the skills you need to be successful while in school, but doesn't necessarily care the weight of option 1 or 2. Firstly, it doesn't give you any grades so right there you aren't really addressing your lower than average GPA. Option 3 is best for those who have a strong GPA but maybe lack those quant/analytical components and want to demonstrate they can handle it. In other words, it's a better additive than substitute.
I would recommend you start with options 1 and 2 and see what fits your schedule and goals best and go from there. If you have any questions, don't hesitate to reach out!
Bhavik
