For me, the only way is to work at school. I stay every day until five thirty, and I actually get more done in that time than I do during all the free time in my weekends. It just helps so much to be in an environment where I pretty much can't get distracted, because there's nothing around me that's interesting to look at.
This is what got me from doing absolutely no revision at GCSEs to studying myself through to an A in my least favourite subject at AS.