Since this is the Photoshop board let's populate it with a post on the namesake of Photoshop: how to do basic editing of photos.

Note: This is for both digital photos and film photos that have been scanned and turned into digital format.

The key here is streamlining workflow. So usually, even before you think of opening up the photos in Photoshop. make sure you have deleted the ones that are too blur or are not satisfactory. If there is one thing Photoshop can't fix, that's overly blur pictures. So you can either open the photos up in ACDSee and see each photo at a relatively high resolution (I usually suggest around 75% of your screen at least to check for blurry images), and then delete them or make a note not to open them up in Photoshop.

Another way is to make use of Photoshop CS's File Browser, which you can access under the "Windows" menu. By default the window for previewing the photo is quite small, but if you move the meta-tags and other menus away you should be able to preview the photo quite well.

Now open the photos up in Photoshop. First thing you should do is adjust the colour of the pictures (I'll cover black and white later). DON'T use Auto Levels, Auto Color and Auto Contrast. They cut out the information from the original picture. Try, instead, using Curves, which is under Edit > Adjustments. When you open up Curves you will see a graph and a diagonal line. We'll leave the line for later. Note the three eyedropper icons at the side. Click on the middle one (grey in colour), and then click on your photo a region that is SUPPOSED to be white. (This is kind of like setting your white balance) To get good skin tones you're supposed to click on the whites of people's eyes or their teeth (if their teeth are white of course). If you get a colour cast that you like, remember to make a snapshot of it. I usually make several snapshots, and play around with the eyedropper quite a few times before I settle on a particular colour cast I like.

After that you can click on the black eyedropper and select the region of the picture that is supposed to be black. Shadows are usually lighter than black, so try a few areas. The white eyedropper I have hardly used, because of the strange results that occur, but you can fiddle around with it too.

The diagonal line in the graph of the Curves dialog is quite intuitive. Basically drag the line to change the shape of the line, and your picture will change in terms of contrast. It's really quite complicated to explain the effects, so just play around with it, you'll understand.

After adjusting using the Curves dialog, there isn't usually any other colour adjustments left. Sometimes I open up Levels (also under Edit>Adjustments) and check that the histogram (the graph in the Levels dialog) is a good one. A good histogram looks like a normal/bell curve, where the middle portion is relatively full, and less in the extreme left and extreme right. You can move the little triangles below the histogram to change the contrast, but usually the curves is a better option since you don't lose data from curves adjustment.

For black and white photos it's usually an easier process. First off I'd convert the photo to Grayscale (Edit > Mode > Grayscale) so I'll have a true black and white photos, and then play around the Curves dialog as mentioned above, only it's easier because you don't have to deal with colour cast, just the overall exposure of the picture.

If you've scanned your photos from a film roll, it's worth your while to then zoom in to your photo (I usually zoom in at 100%) and then check the entire photo for scratches, dust and lines. A ten-pixel healing brush usually does the touching-up pretty well.

After that you can save your photo and be done with it!

This is a basic-level photo editing tutorial because this is just adjusting colour and clearing dust (usually that's all I do to my photos). I know there are tutorials out there that talk about cropping, burning and dodging, and more advanced stuff like replacing backgrounds and the like, maybe I'll cover a few of these later.

Any comments and suggestions? There are lots of ways to do basic colour adjustments, this is the method that I find the least-damaging to photos and easiest and most consistent. But of course, the best thing is if the photo was well-exposed and doesn't need any colour correction at all...