A lot of undergraduate math subjects have a small set of tricks. If you learn 3, you get a C, learn 5 and you get a B, learn 7 and you get an A. You must survive that, but often those tricks do not give you great insight. Keep your eyes open for the exceptions: power series and complex numbers, linear equations, fourier series, etc. Those are the subjects that you really want to take to heart. The subject of differential equations has a dozen tricks, but the basics are really fundamental. You can tell that if there is an entire math class on a subject, then you will see a bit of it in the early classes that you should pay special attention to.
For practice in solving problems, I always recommend the Schaum's Outline series.