I use PE 4 for all my photos. I am not using actions or curves. When importing raw images with Bridge, I make changes to temp, tint, shadows, brightness and sharpness. On shallow and many strobe images the auto functions are close enough for hasty processing, but usually the brights get a little blown out. If auto does not work I try the levels eyedroppers on white or black parts; haven't used grey on tanks but have been meaning to try. If I can't make the right progress that way I use the black, grey and sometimes the white sliders and then move to color variations; on a rare occasion hue/saturation. Then shadows/highlights, resize, sharpen and save. If you are going to crop, it is best to do that right after raw conversion (import); some of the various changes are affected by what it's working with.
This takes some time, but I find that each image is different, so using the same adjustments (action) on all does not float my boat. I hope to eventually have ~9 actions that will cover things in general, but I am somewhat of a procrastinator; said that 3 years ago.
Nearly all my gallery images were processed that way. I sold many prints processed similarly with Elements 2. I have PS 7 and CS 2 on older/slower computers, but full PS is cumbersome IMHO. Most underwater photographers are wasting money by buying full PS(CS), again IMHO.