If the visa officer finds that you aren't financially stable and can't sustain living expenses in Canada, your visa can be denied. You must show that you have enough money to stay there.
If your chosen study programme doesn't match your academic background, you may be questioned. You should explain why you're changing fields.
You must have adequate academic credits as required by your educational institution and the Canadian government to get a student visa.
You need an acceptance letter from Canadian college/ university to apply for study permit. The candidate must also meet all requirements for an applied programme (course).
Student visas require a minimum IELTS or TOEFL score to prove language proficiency; get it in a good number.
If a visa officer finds you a potential immigrant, your student visa can be denied. You must convince the officer that you won't stay permanently after your graduation.
Bring all important documents to the visa interview and order them so the officer can easily go through them.