I am by no means a CSS expert...but I like what it can do, and I have learned a lot through trying to solve problems that I have had as well as helping out people with some of their difficulties. Like a few others around her, I often grab style sheets and just mess around with them to see what happens when I do this or that. I'm also a big fan of Firebird/Mozilla, as there are some excellent extensions available which can help you narrow down problems. The Web Developer's Toolbar, the EditCSS extension are just two I can think of off the top of my cube.
Also, if the CSS works the way you want it to, then there is nothing wrong with it! Sure, maybe there might be some shortcuts to save you some typing and the like, but if it works, it works, so that means you have done what you have set out to do. As with most things, CSS allows 10 different people to arrive at the same destination 10 different ways; all the while being totally valid. Keep slogging away at it! That's the best advice I can give. :)
Oh, yeah...have fun, too!