Peer mentorship is not as helpful at this stage in life. You have opportunities for alum and professional mentorships, some professors are incredibly helpful. You can volunteer to mentor undergrads if thats your thing. Clubs will provide lots of support in prepping you for your careers and many will match you with 2nd years to help you prep for interviews, advise you on recruiting and the like. How you utilize that relationship is up to you and the other person.
My advice is you are better off getting a mentor who is an alum or a professor than a fellow student.