I've not got an 8080, but I'm on my second Oly. One good bit of advice I was given was to set the EV to -0.7. Digitals tend to over expose as they are optomised for land photography in bright sunlight. I shoot ISO 200, noise reduction on (unless I want to shoot multiple shots). With 8MP you may be able to get away with 400, depends on how big you want to print. Usually shoot using aperature priority. Note that Olympus tends to offer f2.8 all the time in auto, so thats why I shoot A. Read up about white balance and set this at depth, If the 8080 is similar to the 7070, you should be able to store 3 WB settings, so can have a different one for different conditions (depth) etc.
If you have access to a pool or somewhere like Stoney, do one dive photographing the same thing on different settings. Also useful to do this top side. The photos are virtually free, but you'll need a very sympothetic buddy.
Lastly, take a look at digigreen if you are shooting in green water (
http://digigreen.net/digigreen/index.php). Plenty of advice there.
Rob