Photos should be professional in appearance. The biggest element is a clean, uncluttered background. You may also wish to have the subject wear business formal clothing. Photos should be in color. As far as electronic files go, a 256-color image doesn't reproduce well, so please use a higher color depth.
Electronic photographs are preferred.
Although SD Times has the ability to scan photographs or even slides, that causes delays and special handling. We are much more likely to use a JPEG or TIFF file. Name the file in a meaningful way. If a freelance writer asks you to send the electronic file to an editor, please indicate in your covering email the writer's name, as well as a rough gist of what the story may be about.