Your shot could be just perfect for potential buyers, but if an important part of the main subject is missing, they are most likely to look for something else. Including the entire subject in the shot is a good idea. Learning how to crop photos can help you create images that will sell well.
Appropriate cropping can strengthen the composition, making the shot “anonymous” or drawing attention to a particular area or an important detail in the photo, like the example in this article. But it is better to avoid “painful crop” when shooting people. Don’t crop off hands, feet or heads… It is rare that a photo sells well when a body part is awkwardly cut out of the frame. Of course exceptions exist, but here is the difference between stock photography and artistic photography. If designers need to crop the image, they will do it, and it is better to leave it up to them.
On the other hand, photos featuring close-ups of body parts can be very successful. Eyes, lips, hands, feet… If you are shooting a series, include some close-ups as well.
Images can benefit from appropriate cropping, and you can use image format to strengthen the composition. Horizontal, vertical or square? Format of your photo can greatly influence how it can be used. If you are shooting a series, it is good to include both horizontal and vertical versions of the image to make sure designers have enough choice. Square photos look really good and create a feeling of balance and harmony. Though if you crop a photo to create a square version, it will become smaller and will cost less on websites where images are priced according to their size.
If you want to learn more, here is a very good article – 15 Easy Tips for Cropping Photos Like a Pro.