-- Spend some time after school each day, and some on weekends too,
working on all those problems that were assigned for homework during
the semester.
-- As soon as you know that you can't possibly understand something, make
an appointment to sit down with your teacher, or with a tutor, and work on it.
Chances are that the next topic is going to build on this one, and if you don't
understand this one, then it won't support the next one.