I'm weak At math! How can i prepare to take calculus?

I have a very weak foundation in math as I went through an online cyber charter school, and though I got straight A's, I felt like I cheated my way through it. In college, I tested into precalc, but took college algebra and BARELY got by with a B-. I found it very challenging and the B- doesn't really reflect how difficult I thought the class was as I clearly don't understand foundational concepts.

What can I do to prepare for calc? I'm planning on taking precalc and then calc, but I want to ace them. I was looking into a trig course on coursera but you have to pay for the full course... That's the only trig course. Does anyone know any good learn-to-calculus books or online courses I could work through BEFORE I take the course?

I'm worried about math. I do well in my science classes and have a strong interest in them but have always struggled with math. Thanks so much for any advice!