The Career Planning Service at McGill offering all McGill students with help in their career development, including job searching, by providing individual advising, workshops and other resources. More specifically, they could help you with editing your CV/cover letters, general interviewing skills, and searching for your interest.
CaPS also provides a database of job postings called myFuture(https://www.mcgill.ca/caps/students/services/myfuture). It is an excellent source for finding out the latest opening both of internship or full/part time opening position at various companies.
For more information of CaPS, go to: https://caps.myfuture.mcgill.ca/students