YOU are asking ME for UW photos tips! Oh my! I took my first UW picture at the end of December last year! I know virtually nothing about UW photography.
BTW - I’m using an Olympus SP350 in and Olympus PT 030 housing. No strobes. Just internal flash. That whole set up was less than $400! I’m looking at spending another $50 on a Magic Filter….
http://www.magic-filters.com/
The cost of the equipment has nothing to do with the quality of the photos. I scored an "A+" on a final project back in university with a series of photos taken with a pin-hole camera made from a box of Quaker Oats and home-made glass-and-gelatin slides!
I do operate in manual mode, though. I have the "film" speed set at ISO 100. The f-stop at 5.6 and the shutter speed at 1/120 s. I do use auto focus and have it set on center spot. I may try bumping the ISO to 200 or higher on my next trip, though.
The big thing to get your head around is that, under water, we can use f-stop and shutter speed to control the amount of light and the amount of color we let fall on the CCD in a very big way! We don’t just use these values to control exposure and depth of field.
Dump the "auto" modes and "scene" modes, get a couple of good books on UW digital photography and start experimenting. Pools, lakes, ponds, rivers, quarries, large puddles…
You should look at these links for a few really good tips:
http://www.yellowtangsoftware.com/purpleink/blogs/index.php?blog=5&cat=37&page=1&paged=3
http://www.yellowtangsoftware.com/purpleink/blogs/index.php?blog=5&cat=37&page=1&paged=2
http://www.yellowtangsoftware.com/purpleink/blogs/index.php?blog=5&cat=37&page=1&paged=5
http://www.yellowtangsoftware.com/purpleink/blogs/index.php?blog=5&cat=37&page=1&paged=1
http://www.scubaboard.com/forumdisplay.php?f=92
http://www.scubaboard.com/forumdisplay.php?f=3
When are you headed back to Southern California? Perhaps we could get together and dive a bit.
Cheers, USMC Ret!!! 
Ian