You can expect to get some great, colorful shots from your DC500. You cannot expect that EVERY shot you take will be great. That is why professional photographers take so many pictures but when you go look at proofs, they only show you about 12 shots!! Yes, lots of the photos you see online are tweaked.
With basic photoshop commands you can take the red, blue or green levels up or down or saturate your pictures etc, but lots of your pictures will not need any 'correcting', while some of them will be beyond correction. Even with a strobe, subjects more than about 6 ft away will still have a blue hue to them. To get the best color stay under that distance. Turn off your digital zoom and don't really depend on your optical zoom. Remember, you can always crop your picture later, especially with your 5 megapixels. Reread the section on the 'shark mode'. It is not something that you can just set and go. What you need to do is find a subject, focus the camera on it and push the shark mode button. This will set the camera to remember the distance and lighting settings from THAT picture. That way you can take another picture FROM THE SAME DISTANCE without having the shutter lag. (You will still have to wait for your strobe to recycle) If you go on to another subject or you decide to try a closer shot or one from further away, your image won't be in focus. The exception to this is a subject that is beyond 6 feet away. At that point the focus locks in an infinity mode and so the 'shark mode' would be great for capturing those big peliagics that you might not really want to be within strobe range of anyway. My best pictures tend to be the ones that I take between 2-3 feet from my subject. I am still trying to master the super close macro. My biggest suggestions would be to take more than one shot of your subject and always try to get the eyes of the fish/animal in your shot. Get on the level of the creature when possible. Shots from above are generally not very satisfying. Shooting from under a turtle or a shark can create a nice sillouette picture. Outside of that, take your cables with you on your trip so that you can hook your camera up to the computer or to the tv to see in a larger format what you did right and what you need to work on. You will be surprised at how quickly you can improve your skills. Most of all. Have fun and enjoy your dive!!!
