I'm not sure how you currently master, but I find that it's better to use a lot of subtle compression at different points throughout your mix, rather than taking a track with lots of dynamic range and slamming it into one compressor/limiter. find out which tracks and busses in your mix can get away with 2-3dB gain reduction, and make sure that none of the tracks have any stray huge peaks. that way, when you finally get to the mastering stage, the compressor and limiter don't have to do as much work, which makes it just a tiny bit more transparent. (although at the end of the day, the louder you want it, the more you have to compromise with some squashing)