Don't use any plug-ins on your master fader> NOTHING, NADA
Group all of your faders togerther when you have your mix finished. Take the master fader down about -5 or so to leave you some headroom on the other side (since you grouped all of the faders should move down with master).
You will then want to bounce your tracks down in 24 bit multiple mono (this will ensure the best quality of bouce) Convert after bounce!
Start a new session, this will be your mastering session.
Choose "import audio to track" from the file menu. Find your L and R files that you just bounced and click add. Once you hit enter it will import your multiple mono tracks. Then you can go to town on the compression and limiting.
Since you left some headroom, you shouldn't encounter clipping. Just keep in mind that in a compression situation you might not see all digital clipping. When you compress you can distort the sound and still not have any clipping that you can see.
You can import all of your tracks to this session and play them in order. Compare volume and mix so you can get a good solid level. When you have mastered your track highlight each song individually and chosse bounce to disk (you will do this for every song) Bounce Stereo Interleaved and 16bit so you can burn it to a cd.
bam! you have mastered your disk (sort of) but you'll have most your desired volume
Check out
www.digidesign.com
Click on digizine and then on groundwork in the bottom left corner
You'll find some great articles about this stuff.
I read them all twice and it's a wealth of info.
Good Luck