If you are interested in photography you will probably already know what a RAW image file is. If not, put simply it is an unprocessed image from your camera that represents the "as shot" state.
You can of course have your camera do the processing for you and apply things such as; white balance, sharpening and exposure. If you want to have greater creative control over your images, shoot in RAW rather than JPG and process the images on your computer rather than in the camera.
Ever noticed that photos on some websites really has nice vibrant colours (no I didn't spell colours wrong, this is how we spell it Downunder - I digress) that seem to really catch your attention? Yet, your photo's are somewhat muted and dull in comparison.
With a very simple technique in the GIMP you will have your photos looking great in no time. Just one thing that I will say at this point is that you can make a good photo better but you can't make a poor photo good. So, before you start thinking I can fix all those duds, that's not what this tip is all about. This is about taking an already good image and improving it.