The best thing would be to first test the room to see what exactly is what, as in what freqs are giving you problems, something like the XTZ room analyzer is a brilliant little tool for measuring your room, you can has a guess at what areas are given you problems. You can start with some simple methods to get you started, such as treating your first reflection, that's the sides, floor then ceiling. Then some bass traps in the corners to give you a nice tight bass response. Things such as carpets, curtains, can help, but only in the upper midrange to treble regions, trapping 60Hz downwards is much more difficult if you have problems in those areas, it depends on speaker size, and room size.