The cost of housing varies widely, but international students, like French students, are eligible for housing assistance.
It is reassuring to make housing arrangements before leaving for France. This is possible if you are able to secure a room in a university residence managed by CROUS, the regional student-service agency (although spaces in CROUS buildings are largely reserved for recipients of French government scholarships and students participating in exchange programs) or if you plan to attend an institution that maintains its own student residences.
Otherwise searching for housing from outside the country can be difficult. You won't be able to visit properties and make fully informed decisions. It may also be difficult, from a distance, to persuade a property owner to let you sign a rental contract or convince him that you have someone who will guarantee payment of your rent.
For these reasons, many international students choose to find temporary housing for their first few weeks in France. They use that time to look for a more permanent arrangement.