If you want to try your hand at home mastering, I'd say wait until you have all of the songs for your project completed. Don't try to master your songs individually.
When I master music for friends (who, believe me, are in absolutely no position to be sending their work to a mastering house) I load all of their songs into Wavelab and play them against each other. That way, the best sounding songs quickly rise to the top and tunes with sonic deficiencies stand out, too.
"whoa! That one's pretty muddy!" and "Boy, that sure is quiet..." are commonly heard.
Then, I try to make all the songs sonically similar to the best mix on the album using whatever tools it takes. Compression, leveling, stereo field manipulation (which should have been done in mixing, I know) and EQ are commonly used in very sparing amounts.
Its a balancing act. There is no real recipe as it completely depends on each individual mix and how they sound as a project.
I'd caution you, though, that mastering really is tricky business. If you don't have a really accurate monitoring system and a good listening environment, you will make changes to your material based on your speakers and room. It won't sound the same when you put it on a different system.
The way I see it, I love to play with my stereo mixs and see what I can do to them. I love helping poor friends get their demos sounding a bit nicer. When my own project is ready to be burned to 1000 CD's, though, I'm sending it to a mastering house.
Take care,
Chris