Certainly you should practice problems as much as you can to get the hang of them. In addition, the question title contained mention of algebra, and I don’t know if this is relevant to the difficulties you’re having, but having a good foundation in algebra, trigonometry, and functional analysis (just being familiar with the general behavior of different classes of functions) is crucial for calculus. Calculus draws all of these elementary areas of mathematics together and a gap in understanding in one of these areas can cause a gap in understanding the calculus that involves them. Some of the problems you’re having with calculus might be due to some things that you didn’t understand about an earlier math.
Also I don’t know how much it will help, but this is a particularly nice website that contains online course notes for algebra, calculus, and a variety of other courses.
http://tutorial.math.lamar.edu/
I’m a sophomore engineering student in college and I still check this website every now and again for math help, it’s pretty good.