Check the system requirements. If your system doesn't have enough free disk space (some programs use up a lot) or if you are on an operating system not supported by a newer software package, you won't be able to run it on your computer.
What kind of training do you need? Novices may want a program that will guide you through the simplest tasks, such as red-eye removal or cropping images. Will there be support (tutorials, guides, forums, FAQ lists) to turn to once you get past the basics and want to move on to more advanced edits?
How about a free trial? Many companies are good about offering a 30-day free trial before purchase. Before buying, give it a shot and see how it goes. If you hate it, move on to something else with nothing lost. If you love it, start shopping for the best deal.
Check for upgrade pricing. If you want to upgrade to a newer version of software you're already using, many manufacturers, including Adobe, offer discounted upgrade pricing. For example, Photoshop CS6 retails for around $700, but users of CS3, CS4 and CS5 pay only $200.
Balance features with ease of use. Photoshop does literally everything, but if you are not heavily involved in photography or graphic design, experts suggest starting with something more basic. It will take time to learn how to use all of the features, and it's easier if you are transitioning from an Elements-like program.
Which file formats are supported? You want to be able to import and export a wide range of file formats, including BMP, TIF, GIF, PICT, EPS, PSD and JPEG. If you have a higher-end digital camera and want to shoot in RAW format (where no processing is done by the camera itself), you'll need software that can process RAW files.
Do you want to use layers and masks? If you plan to do extensive photo editing, these tools are essential. Layering allows you the flexibility to try different adjustments without touching the original image. Masks allow you to work on only one portion of an image.
Consider file storage and management. Most photo-editing software includes some basic image management features, so you can organize files and find photos later. Most enthusiast and professional photographers prefer separate databases for this. That's an entirely different category of software and worth checking out if you anticipate taking more than a few hundred photos.
Look for web and social media integration. The newest generation of photo editors allows you to save images in web format and post directly to Facebook, Twitter, Instagram, blogs and other photo-sharing and social sites.
Templates, plug-ins and actions make fast work of simple tasks. Photo-editing software for beginners often includes fun and creative templates for scrapbook pages, calendars, photo books, greeting cards and magazine covers, just to name a few. Plug-ins and actions are functions that are downloaded from third-party sources and can speed up adding specific effects to your images, usually with just one click.
For the casual user, purchasing a program like Photoshop Elements 11 (Est. $100) makes a lot of sense. You may want to upgrade in a couple years, but it's essentially one fixed price, other than add-on actions and plug-ins, which are time savers and fun, but not necessary. For anyone on a shoestring budget and willing to learn its complexities, GIMP's free software is a reasonable choice. It gets trickier for Adobe Photoshop users.
Adobe is currently transitioning from a one-time download model to a subscription model. You can still download Adobe Creative Suite 6, but going forward all upgrades to that software will be available only in the company's new venture: Creative Cloud. A membership ($50 per month) gets you access to Photoshop, Lightroom and other tools as well as cloud storage for your files. You'll also get free software upgrades for as long as you remain an active member. If you cancel your membership, you lose access to all software in the Creative Cloud as well as your online storage. For now, Photoshop Elements is not part of Creative Cloud.
Deciding whether to become a Creative Cloud member or buy the stand-alone version depends on your individual needs. Read more at Laura Shoe's Lightroom for some insights.