Thanks all. I have to credit my success to the wonderful photographers here on the RC photography forum who have helped to steer me in the right direction. Sure, I've done a fair amount of "regular" photography compared to the average person, but reef tank photography is a specialty unto itself and without guidance from those here in the know I would still be floundering around using auto everything wondering why some pics came out ok and not others.
Some basic items: Shoot straight through the glass, not at an angle! Use manual focus so you can be sure the focal plane is where you want it. Use a tripod and a remote shutter release so as to eliminate camera shake and jitter. Turn off all pumps so water motion stops. Shoot in RAW so you can white balance accurately and achieve proper colors. Avoid center composition. For me, using manual exposure makes me think more critically about the exposure instead of just accepting whatever the camera decides. I don't always get it right, but each time is a learning experience.
And don't be afraid to post your pics. Constructive criticism can be a valuable learning tool. The people here are really very helpful.