Usability
Good cameras can take pictures, display them, and let you scroll through menus quickly without having to stab buttons again and again to get something to work. Compare models side by side to gauge their speed, as well as the usability of the menu settings and functions.
After all, you don't want to spend your time trying to figure out how to swap between stored images and photo-taking modes when capturing that once-in-a-lifetime pic.
A plethora of menu and usability choices is out there. Most cameras use LCD panels to display your menu options, while others also employ dials for various image and setting options. Again, the quality of the camera you buy will determine the number of functionality features on the camera.
Focus Options
All digital cameras have the option of using auto focus to focus on the subject. Higher-end units may also offer manual focus, which will allow you to focus the image you are taking yourself. This can be useful for close-ups or situations in which the camera can't get an automatic focus lock.
Auto focus is great for users who want to keep photo-taking simple, but won't please the avid photographers who want more control over the focal length or depth of field used in the image (see "Photo terminology" section for more on these terms).
Also, look for a macro focus option. This will allow you to take very close-up photos of subjects on which you wouldn't otherwise be able to focus with a normal lens. Macro lenses can focus on a subject as close as 2cm or 3cm.