Identify your passion and reason(s) for wanting to become a graduate student. Write them down, type it up, post it large and visibly on your desk or wherever you do your work so that it remains a constant reminder of why you are doing what you are doing and will motivate you through the hard times that every graduate student has and does go through, so that you can always see the light at the end of the tunnel.
Be prepared. Look around first and then come here. Do your homework when you're looking at programs and remember that you stand a real chance of working with OMAFRA and OMAFRA connected researchers here. They really are the best.
Make sure you need grad school for your future career before you do it. Reach out to other grad students while you're in undergrad; most people will be more than happy to share their experiences.
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.
Pursue research that you truly believe has the potential to improve life. Knowing you are working toward something more than just a degree can help you find the drive to make it through the difficult or dry aspects of your time in graduate studies.
Your time in graduate studies will provide many opportunities, but don't lose touch with yourself. Take the time to do what you need to in order to maintain your sense of purpose and direction, then live out of that. Don't be afraid to try new things, but remember that no one can do everything. Be selective.
A right step taken at a right time completely changes your identity. I won't say that your academic journey will be easy, but I am sure it will be worthy.
Grad school opens doors! SO many doors were opened up for me just in the last two years of my degree.
Make sure you choose an adviser who is well-known in the industry because they will help you grow quickly in the field. I saw my adviser as a professional mentor and I'm able to go to her with questions about the industry. She has given me so much insight into the future of our professional field which has helped shape my future career goals. Take advantage of all the mentorship opportunities that you can. Grad school is the BEST place for that! Finding mentors when you're not a student is hard. Being a student is a great excuse to find mentors who will be so strategically useful to you, if you take advantage of your time here!