Getting a 30 on the ACT?

I'm yearning to go to Mcgill University in Montreal. I'd like to study French Literature and possibly English/Theater. I only recieved an 1140 on my sat, but I can't afford to take it again. My application fee will be waived for the ACT, so it's my only option. How can I get a 30 when I got the equivalent of a 25? My best score on the SAT was writing in which I got a 690. Are there any tips to help me get the score I'm aiming for? I'm in my senior year, and I'm feeling inadequate and rushed.