Sharpening and blurring areas is a great way, and resizing can help a lot too. You could go through the painstaking process of smudging out some of the pixel-y areas, but that can make the image look a little fake (if it's of a real person). If you're using Gimp, there's a great plugin called GreyCstortion that I can send you if you want. That works nicely. There's also something I've heard about called Topaz, but I'm not 100% sure about what that is. Edit: Here's a nice tutorial: [x]
