I would tell any prospective grad students to visit the campuses they are applying to, and talk to students in their program(s) of interest! A major factor in my staying at Guelph was the campus community, and knowing that I would be supported throughout my studies in not only my academics, but also through the social atmosphere on campus.
This is a program that is very responsive to student needs, so if you have a question or want to pursue a line of discussion, be sure to ask! There is a considerable commitment to participants' career and personal growth, as well as to the more formal education elements. I appreciated that "all-around" approach.
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.
See graduate school as an opportunity to grow in many different ways. UofG has plenty of wonderful research opportunities, and a big part of being a researcher is the chance to communicate your research to different audiences. Graduate school is an awesome opportunity to become a more well rounded person from developing problem solving skills as a researcher to sharpening communication skills, all of which are crucial for any walk of life you end up travelling down.
My first piece advice to prospective grad students would be to find a lab or an advisor that you mesh well with and are excited about working with. If you are on the same page and feel comfortable from the start, it makes all the difference. After that, trust yourself and your abilities! You are capable of more than you think.
Be patient with yourself. As a student your job is to learn, and by necessity, fail. Solving the problem and having the right answer isn't always the same thing.