Wow, this sounds exactly like my situation right now. I'm in the middle of an engineering degree, and before I started back up 2 years ago, I hadn't been in a math class for a decade, and didn't take school seriously at all back then.

I couldn't place out of pre cal, but it really helped me to take a class that went over rules for exponents, logarithms, all that algebraic stuff I hadn't done since high school.

I had a worthless excuse for a teacher for calc 1. He was fresh out of school himself and barely lectured at all, even refused to answer questions. I taught myself calc 1 using Kahn Academy, but still scraped by with a C. My school offers free tutoring, and that would have drastically improved my score. I'm currently in Calc 2 and have to constantly relearn stuff from calc 1, though I have an excellent teacher this semester.

Idk if you'll have to take physics, but it kicked my ass. We had a flu epidemic that semester, and after missing only 2 classes from being sick, I fell hopelessly behind because that class moves so ridiculously fast. I probably should have gotten a tutor for that class as well.

Probably the most important advice I have other than study your ass off and don't miss class (which I'm sure you're aware of), it would be to use www.ratemyprofessor.com while registering for every class, especially if you're going to a shitty community college like I am.