The ideas discussed in this video brought to mind one mistake I see photographers making when they're selling their photos on custom products in the Zazzle marketplace. There can be a tendency of new (and some experienced) shopkeepers to want to showcasing their entire photo on the custom products available at Zazzle rather than fill the design area available.
Below is an example of what a rounded corner mouse pad would look like if I fit the photo to the mousepad. It would have large white borders.
Below is what the mouse pad looks like when the image fills the entire design area.
Lake Tahoe Mousepad by annaleeblysse
View other Shore Mousepads
Cropping, even extreme cropping, can be our friend. Cropping off some of the Lake Tahoe shoreline doesn't take away from the subject of this photo. We can still see the blue water and shoreline. But, large white borders at the top and bottom definitely distracts from the photo. Some customers might want white borders, but they're so few and far between.