When restoring an image I like to work from a digital copy, that way the data contained on the original image is never altered. I also don't want to take away from the story told my the wear and tear. You can tell a lot about a photo by how it has aged.
If you choose to scan your images on your own there's a few things you need to remember.
1. Scan your images at a high resolution. Most scanners have a default of 300 dpi (dots per inch) That's great if you just want a small image for the web but to get a good quality scan you need to move it up to 600 dpi or higher. So you can enlarge it and remove flaws without getting a boxy pixelated jumble of data.
2. Scan in Color even if you images is black and white. Black and white images have their own color tones and style. It's nice to preserve that original coloring in your scan even if you don't plan in keeping it. It also makes it easier to restore the image. Stains, water damage, and sunlight often alter the color of an images not just fade the data allowing you to select the part of the image needing restoration based on the color change not just the fading.
3. Save as a jpeg or tiff. I have heard arguments for both file types. Personally I work a lot with jpegs so that's usually what I save them as. It's usually your default file type on your scanner so you don't need to change anything. There are some people who claim tiff files are the way to go but most print companies and photo sharing sites like them in jpeg format so that's what I tend to save mine too. But you need to save it in as high of quality as you can for restoration purposes. You don't want to get a good scan with lots of information then have the computer compress you data.
The most important part is to just get your images scanned. You want the best quality you can but even a cell phone snap shot of a photo that aunt sally has is better than having nothing, so don't be so scared of doing it wrong that you do nothing at all. Best of luck in your scanning adventures and can't wait to try my hand at restoring your old photos. Also there's plenty of companies out there willing to scan your images including me. Together we can paint a beautiful family tree and see how we are all connected.