I'm not well versed in this at all, but basically what I want to do with my mixes is be able to generally level off every channel that with compression so the mix is 'flatter' and averaged out dynamically before going through a mastering chain. What's been happening with my mixes previously is they're very dynamic but nowhere near a commercial level, so when I get to mastering I end up running a multiband compressor and maximizer extremely hard to compensate for this. Is RMS compression the best way to go about this? What do you guys do to compress during a mix down?