There are many online resources to help you with math. I sucked in math back in high school, so I relied heavily on Math Advantage CDs to guide me through. In college, I stuck with assigned textbooks or Khan Academy (which is really great btw).
For calculus, I used
Paul's Online Math Notes and
Visual Calculus. Very helpful in getting difficult concepts clarified.
And of course, you can utilize your professor's/TA's office hours to ask for any clarification/help. It helps because you get a personalized feedback/instruction on topics that weren't covered well in lecture.
Trig sucks. It really does. All the stuff on building triangles and deriving random identities is a total waste of time. But there are resources you can use (including those I mentioned above).
https://www.khanacademy.org/math/trigonometry/trigonometry-right-triangles