Richard,
There is a thread on the recording forum about mastering as related to loudness. I also struggle with it. The best advice I have and I got it from Andy K is find a reference CD that you want to sound like and keep experimenting until you have it. Another thing I've done is pay attention to the volume settings on my vehicle radio or CD player and try to get recording to match in volume level at the same setting.
I think the compression issue gets us all on mastering. I have found that most problems are in the initial recording tracks and/or mix. I try to get good individual tracks anymore that pretty much stand on their own and then use very little compression or limiter on the mastering. I still don't have it right yet. I'm also limited in tools as I use a stand alone machine and not a computer. You have to just keep trying and each generation gets better.
Dan