Yes, I do have to say that you can't beat doing questions, however, that is really for when you're staring down the barrel of your exams.
We're not quite there yet? I must say I find reading a textbook really useful: I just read the tricky bits slowly or even out loud - great for when you are actually studdying the topic, or have some idea of what it's about....but it's got to be questions and lots of them.
On textbooks, it is really important to have a good one. My physics teahers gave us about 6, and i really only like one...but I do find it really helpfull to have a bit of a read of something that wasn't explained too well or when you weren't paying attention in class!