Jeffrey P. Fisher has several articles on this specific subject. He's one of the hosts on the DMN forums.
You can see his V/O articles at http://www.jeffreypfisher.com
It should probably also be said that there is no "formula" for doing this, or there would be a whole lot more V/O artists out there doing their thing. Moreover, there wouldn't be crappy V/O any more either. It's not like you can say...."Get a Sennheiser/Shure/AKG/Teledyne/BK/AT/whatever brand and model#, then use XYZ EQ set to X setting, then use XYZ compressor set to X level" and you'll have great V/O. Ears are a huge part of this, same goes for a great voice.
Exactly, you can spend all the money you want on equipment, but if you don't have the voice it will never sound good. Althought I have heard some pretty amazing things come from guys who have a really average voice. Processors can do wonders, but the more you use them the more "fake" the voice begins to sound. I was in radio for about 5 years and still do the occasional voiceover for commercials and stuff. I saw lots of jocks that would crank the reverb and the bass to try and make their voice sound fuller than it really was and all it did was make it sound really fake.
Less is more!
A while ago (quite a while actually) someone on ths forum suggested raising the voiceover some 2 or 3 dB at around - was it 1K?. I suppose different voices will have their own sweet spot (haha) where that method will really work.
It is also a question of playing down other audio tracks that might muffle the voiceover. Make room for it. Not only when it comes to level, but also in terms of frequency. To give a very crude expalanation: If you raise the voiceover at 1K, lower everything else at 1K.
Tor
I just installed the upgrade of Sound Forge to version 7, and if you have it, note that you can add another pair of VU meters to the default ones by right-clicking and choosing PPM meters, which reflects the "apparent loudness" of a soundtrack. This helps you balance the perceived volume of a track. If this makes no sense, the idea is similar to the way commercials on TV sometimes seem three times louder than the program content--somebody normalized the commercial volume at a higher level, which may not show on the green VU meter but would show on the multicolor-PPM meter.