The single most important thing to adjust is the white balance. That's why pictures on camera phones look so colourless and blue.
As you shoot raw you're in the best position to make these adjustments, as they're not adjustments, merely changing the way the photo will be produced from the raw data.
Try Lightroom from Adobe instead of Photoshop. Get a trial, you'll immediately never use photoshop for photography again :)
As said, lowest ISO is important for colour, turn off flow to slow corals etc down which means you can get away with a slower shutter speed, which gives you window for lower ISO.
As for aperture, it's the least important. Shoot wide open for maximum light to allow you to have fast enough shitter speed and low ISO but you might want to a stop it a stop or two to get better sharpness as some lenses aren't very sharp at widest aperture.
Get some pics up! :) good to see another raw shooter around. :)