To begin with, you must be able to prove that you have been accepted to a Canadian university. Generally, a letter of acceptance will be sufficient. As the Canadian government does not want to let people into the country who could be a threat to society, you must prove that you are a law-abiding citizen with no previous criminal record. You will need to obtain a certificate from your local law enforcement office showing that your record is clean. Students accepted into Canadian universities also must show that they are in sound health. It may be necessary to undergo a medical examination. Finally, you must be able to firmly impress upon the immigration officer who interviews you that you intend to leave Canada once your course of study finishes.
Students entering Canadian universities must be able to demonstrate that they have enough funding, not just for tuition and books, but also for their living expenses during the entire period that they would like to study in Canada. In addition, you must be able to provide sufficiently for any family members that might be coming to live with you in Canada. Finally, you must be prove that you have sufficient funds to pay for return transportation for yourself and any family members coming with you, in the event that you have to leave the country for some reason.
Some students will not need a study permit to study in Canada. If you are only going to be studying there for six months or less, then no study permit is necessary. It should be noted, however, that even in this case, you might want to apply for a permit, in the event that you decide to extend your studies beyond the allotted six months. You are only able to apply for a permit outside of Canada---so if your stay is extended, you will have to leave the country to extend your stay. Family members of foreign representatives to Canada and members of foreign armed forces are exempt from applying for a study permit.