Now it is very easy to get the knowledge you need through online courses. It is very convenient and helps to get the necessary skills in short lines. I think many people know this site
https://www.coursera.org/, because there you can find many courses and even get a certificate.
It is difficult, but the most important thing is to believe that everything will be fine. Some people don't prepare at all and pass all exams excellently. I advise you to sleep more and to alternate between rest and study. This will help you have a lot of energy to make everything perfectly.
I recently completed my master's degree, and I can say that it was a big mistake for me personally to apply for graduate school, because it brought almost no new knowledge. Perhaps the reason for this is the wrongly chosen university, so I advise you to carefully study this issue. In general, I can say that it takes a lot of time and effort and is difficult to combine with work (work in your specialty)