Some Tips To Get Better Marks in School?

Im in grade 11 and at the midterm of last semester, I got my report card and had some hope to get honour roll. I had a 85 in french, and 70's in my other subjects. I then made it my goal to hopefully have at least 3 80's by the end of the semester...Well, I got my hopes up too high...The end of the semester was about a week ago and I got a 68 in English (I had a very hard english teacher!) 75 in media, 78 in Biology and 86 in french. I was and still am so dissapointed and gave up my hopes for honour roll! I then found out that I dont need to necessarily get at least 5 80's in 8 subjects, I can make honour roll by ending the year with at leat an 80% average! I have a 76.8% student average and im so close to 80! This gave me hope but it will be a very hard goal to achieve! I have math this semester, my nemesis. The highest mark ive ever gotten in math is 70! My other cles I should be able to get a decent grade though. Im hoping I can make it this semester so what are some tips to help me achieve at least an 80, and beyond. In my courses? Thank you! :)