Open up a new document and create a basic bare-bones setting (just the rewire and the mixer) Go to the create button in the menu and add MClass Mastering Suite Combi to your rewire panel (the one at the very top). Select the 8 Band Parallel Compression setting. Then save it as Document 1, that way, when you boot up Reason, it'll become your default. As you create songs in other file names, the Document 1 setting will remain the default.
Everything will seem louder than what you're use to, so adjust the volume settings in the mixer as you compose. I recommend getting monitor headphones if you don't have them already. Samson makes a great brand for the price they're offering: the CH700 model is around $60. It's like having studio monitors around your ears. GREAT if you're doing music with heavy drums.
I hope this works out for you. Trust me, you *will* notice a difference vs. making something without it.
If you get a chance, stop by and give me some honest critique. It's appreciated!
http://www.mybeatshop.com/nilelata
Jes'
FBE