Find what interests you. Many other grad students are much younger than I am and will be entering a life's career following completion of their studies. Looking back, I think it's important to pursue your passion and let the career, money, etc., come from that. During studies, stay on top of things. At the same time, don't neglect other outlets, pursuits, interests: things have a way of connecting in unexpected ways.
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.
Sometimes as an undergrad it's easy to stay 'behind the scenes' and just go to classes and complete what's required of you. But grad school has SO much to offer, and there are opportunities to gain new experiences around every corner that contribute to both personal growth and look great on a CV. I think getting involved is so important, and creating new relationships with faculty/other students is key.
I have found success in graduate studies by having a solid group of people supporting me. Academia can be daunting and difficult, but having friends and colleagues who are like-minded, engaged, and generally supportive has made my journey possible. Pick your department and supervisor with care, seize opportunities, explore new and old interests, maintain hobbies outside of research, and most of all: stay curious.
I would advise a prospective graduate student to do their homework before contacting prospective advisors. Check out their profile on the University website, read their most recent paper, and even reach out to a senior graduate student currently in the lab!
Finding your passion will take you to the right place at the end of the road. Just keep doing your best and appreciate all the opportunities provided along the way.
I advise prospective grad students to network with as many interesting people as possible. Networking is key to finding research opportunities and gaining experiences. Even simple conversations can stimulate new ideas or help solidify original ones.
“I love Guelph for the downtown area especially the farmer’s market, the pubs, and all of the great outlets for outdoor activities. There’s a strong culture in Guelph that creates a strong community feel to the city.”
I heard this quote when I first started my Master's: "Your project at the end is not going to be the same as when you started". Although your overall deliverables/outcomes might stay the same, how it gets done is very likely to shift. Those who are adaptive to change, take proactive measures to complete tasks timely, and are willing to go outside of their comfort zone will be the most resilient.