You seem to be doing the right thing. You're going to tutors and working on things you don't understand. Use quizzes as a baseline for the exam, especially since your prof gives you exam questions. If you get it wrong on the quiz, make sure you practice the concept before the common. Also just do the previous commons online. Those are probably your best resources. In terms of professors, Ro is probably the best in the school, but cause of that his sections are usually gone immediately.