Physics is 90% conceptual and 10% mathematical. The previous poster who suggested going through each problem line by line is very right. You've got to figure out what you know, what you're looking for, and what equations you've got to play with. Sometimes looking at what equations you've got is all you'll need. It's also important to make sure you're variables are in the appropriate units.
If you can't understand the lectures (I couldn't) spend a day a week going over the chapter for that weeks material. Make notes, work through the example problems, and don't give up. I did this exact thing (horrible prof.) and I got an A+.
Good luck, and don't stress.