As has been repeatedly stated there isn't a magic bullet to do this since it involves doing things at many stages of the mix. One of the most important things to learn is how a compressor works. Some programs like
this one is a good learning tool since it visually shows you what parameters like threshold, ratio, attack, and release do. There's also a free demo for it. Anyways, here are some general tips on getting your mix louder.
Compress individual tracks to reduce their peaks and also to color their sonic character. This is a whole science in itself.
You can put a compressor on the master bus to reduce the peaks of the overall mix and glue everything together.
You can use some kind of audio saturater or any plugin that adds some harmonic content which can add perceived loudness.
You can also put a clipper afterwards (I use gclip) to chop off the ends of some of the peaks so the rest of the mix can have more headroom while retaining its punchiness. Beware as this can introduce distortion if you overdo it (you can actually hear this distortion on many modern mixes these days).
Finally you can strap a limiter at the end of the chain at -1db to normalize your track. If you want, you can push the limiter even harder, but too much will suck the life out of your mix.
This is what I did on my Selkies solo mix as can be found in the rate my mix forum. Ozone can do most of these things but not all equally well. Be careful not to overdo things. When in doubt post your mix on the forum asking people to tear apart your mix. You can also listen to other mixes and see how they sound.
