Always ask for help. When in doubt, ask; When not in doubt, ask. Enrolment in graduate courses can be very small, and grad life can sometimes feel isolating; so, try to form great bonds with other grad students. You have a lot in common! Try to take some time off to have fun, and when you inevitably encounter students pulling a tractor in September, do the opposite of what I did; and be cool! If you can, participate in the 3-minute thesis competition (3MT); it's a lot of fun!
To any undergraduate student that wants to pursue graduate school, my best advice would be to study hard, celebrate your academic victories, and don't get caught up on your failures. Everybody has a story of a course they wish they did better in, or a midterm/exam that was an unexpected curveball, but as long as you learn from your past and keep pushing forward, things will work out for the better.
My advice would be that a Masters degree is like a roller coaster. You will have your ups and downs in your research but that is all apart of being a scientist! There is no such thing as a 'bad' discovery.
Remember that research never goes as planned and to not let failed experiments or unwanted results keep you from working hard on your degree. No one gets through graduate school without failed experiments and huge changes in their project plans.
Although I think most prospective grad students have been told about the importance of picking a study/project that interests you, I think it's also really important to take some time to see how you interact with your supervisor and lab. These will be the people you work the closest with for the next several years, and help provide support to you in some of your toughest moments.
My advice to any prospective grad student is to not rush into graduate school without some self-reflection about your passions, what you love doing and what you would like to study. This is because grad school can be a challenging place but also incredibly rewarding as it teaches you how to read critically, learn systemically, and think deeply. As such, I invite potential students to engage in some introspection and self-reflection about your motivations, desires, and commitments as this is a weird (but wonderful) experience distinctive from both undergrad and from other jobs so its important to not rush into anything without thinking.