[bcrdukes]

I'll take a stab at this.

1. As a general rule of thumb, always study using the latest guide. The subtle differences can make or break your GMAT exam and results. I believe the 2020 version has more questions than the 2018 and 2019 version, so proceed at your own risk, and with extreme caution when using the 2018 version. My personal advice is to stop using the 2018 version.

2. There are online tutorials / guides you can utilize, and also in-person and online/virtual courses / prep classes to take (in-person is kind of hard now given COVID-19.) I used Manhattan, while others used Kaplan. There are a lot of others out there. Find one that appeals to you, and suits your schedule.

A forewarning, however. You MUST dedicate your time and efforts into the courses/material, or you will likely fail the GMAT going in to it. To elaborate on that, spend the time to talk to your friends, your family, your employer, and colleagues to let them know that you are doing this, and that they recognize this is something you are aiming for, and ensure that they support you in this. I knew a few people who kind of half-assed their dedication to the programs and failed multiple times to the point where they weren't allowed to re-take the GMAT anymore. Don't let yourself be one of these people.

Are you aiming to take the GMAT towards an MBA? I assume yes. I ask because there are some people who write the GMAT...for the sake of writing it to stroke their ego or something (I don't know but I've encountered a few people who took this path.) You will encounter a few people on the fringe who will write the GMAT for the sake of writing it but with no plans immediately to apply to a school (they could be coasting through life or their careers - we will never know.)

3. The highest possible score one can achieve on a GMAT is 800, so you want to score the highest score possible, so look at it from that perspective instead of asking what score to aim for. In all fairness, your question is valid because certain schools will have a minimum GMAT score criteria i.e. UBC vs. Harvard.)

Having said that, the score isn't the end-all-be-all of the GMAT and your entry admission to the school(s) of your choice. No university in their right mind will publish their entry level requirements for the GMAT score; Maybe a fake university, or a money grabbing university like in India, and there are a lot over there. [Edit] I should add that it helps to network and talk to graduates of an MBA program based on the school of your choice to get a better idea of the process and overall experience. Someone who earned their MBA from Ryerson vs. someone who earned their MBA from Kellogg will have a vastly different experience from the program, and application process.

In addition to the GMAT score, schools will assess and factor in other things like your resume, prior experience, social work, extra-curricular activities, and what your plans and goals are after achieving your MBA (having a solid foundation in being employable helps!) Schools will want to make sure their graduates are advertising and marketing assets to ensure a new round of students in the years to come.

Finally, depending on your academic and professional background, some areas in the GMAT may be easier for you than compared to others. Say for example, someone with a background in political sciences or law may find certain areas of the GMAT fundamentally easier to breeze through, compared to let's say someone who has an arts degree in basket weaving (I'm making up an extreme example for the sake of argument.)

Hope this helps.