Another common problem with photographs on paper is scratches. This photo is a good example - the scratches on the girl's face are particularly bad and will be hard to remove:

Let's assume that grandma has heard you're getting pretty good with computers and has asked you whether you can do some digital magic to 'save' the picture above. If you do a really good job she's promised to make you one of those scrumptious fruit cakes that you love so much!

1. The first thing to do with the above image is... examine it. Do you agree that the tonal range of the image stretches to almost-pure white but there is no black in the image at all? And do you agree that this image is supposed to be a greyscale image without the brown tint that it has acquired over the years (some people like that brown or 'sepia' tint, but it really wasn't what the photographer wanted).
    

2. Next step: convert the image to a greyscale image with Image > Greyscale. Note that some silly people call greyscale images 'black and white' images, as if such images contain black and white only!
    

3. Now crop the image to remove the light-coloured border. If you leave that border then any automated adjustments that you apply will be spoiled slightly by the presence of this large light area which really isn't part of the image.
    

4. Now fix the problem of tonal range mentioned above, to ensure that the image contains a full range of greys stretching all the way to pure black. You could use the histogram adjustment for this, or the curves adjustment (moving the point in the bottom left corner).
    

5. If you think the picture is too light or too dark this can also be corrected using the histogram adjustment, the curves adjustment, or the gamma correction but as usual AVOID USING THE BRIGHTNESS CONTROL.
    

6. Now it's time to attack the scratches. You may have noticed that there is an automatic way of doing this with Adjust > Add/Remove Noise > Automatic Small Scratch Removal. Try it if you like - you might be impressed at the efficiency with which it removes scratches but look closely and you will see it has removed a lot of wanted detail too, such as the top of the girl's hat, her teeth, the dark lines along the edges of the small boy's braces etc, so I don't really recommend it. However, it's true that there are quite a lot of scratches in the sky area so you might want to select the sky (e.g. with the magic wand or the freehand selection tool) and then apply the automated correction. For the rest of the picture I suggest you use the scratch remover tool . It removes removing straight scratch lines by smudging from other side of the line towards the centre. It's thus easier to use than the clone brush but really only is good at removing scratches, as you might expect. If you don't see the scratch remover tool but do see the clone brush then press the triangle next to the brush and switch to the scratch remover tool. When you want to fix the girl's face I suggest you zoom in for this delicate work and reduce the width of the scratch remover tool.
    

7. As a final step, you might want to sharpen the image a bit.

So, did you do a good job? Can you smell the fruit cake already?