I didn't take physics in high school. I'm taking it right now and am getting one of the highest grades in the class.
Basically I read the book, went to all the lecture classes, and did all the practice problems. Also I got a book called "Understanding Physics: Motion, Sound, and Heat" by Isaac Asimov (actually it was ten cents at the thrift store, no kidding...but you can probably find it pretty cheap on amazon) and read that before I began taking physics, I think it helped a lot with concepts.
I'm not sure what your background is as far as math, but I think as long as you're fairly decent at basic math and have a good work ethic its not necessary to take a pre-physics course. General physics courses are usually designed with the assumption that many students haven't had previous exposure to physics, anyways.