They may not take up much physical space, but digital images require a bit of wrangling for easy access and safekeeping.
Use software to sort. Sort digital images easily with photo-organization software that comes packaged with most digital cameras.
Change the names. Add identifying information to your file name, such as "LakeOkaboji_5x7.jpg." If you changed the image to black-and-white, save it as "LakeOkaboji_5x7bw.jpg." That way, when you're ready to print, it will be easier to identify the specific photo you want.
Be ready to search. Find photos using organization software and the keyword you used when naming your files, which means no more hunting through dozens of images to find all the photos of your child's first birthday or your husband's grandmother.
Store them on CDs. Avoid losing your images in a computer mishap by not storing them on your hard drive. If your computer doesn't support burning CDs, you can upload your images to an online service that will save them to a CD for you.
Label them. Any labeling should be done using an acid-free permanent marker.