Be persistent - success is achieved over time. Rome was not built in a day. Above all, develop good habits regarding attendance, assignments and study. Just as you cannot learn to swim by watching someone else in the water, you will not learn the new material presented in every Math class just by attending and watching your instructor. Ask questions - in class and out.
Many people find it difficult to ask questions in a large group.
Never assume that you are the only one with a question and that it is too dumb to ask. When students get confused in class they usually rely on the question askers - the handful of students who regularly ask. Above all, remember that teachers expect you to ask questions and it is your right to ask. Staring at the text or your notes is not study. Chatting with your friends over an open math notebook is not study.