Obviously you want to have good pictures of your products to display. You might want to get them taken by a professional photographer for the best presentation. Or, you would want to at least plan out how you will take them yourself (have a consistent set, good lighting, good camera, models organised if needed, etc.).

The good thing about this system is that it automatically scales the images you upload to the preset sizes (preview size and full size), so you don't need to scale them yourself or do much work with them at all before you upload them. But you do need good originals. Probably the only thing you would want to do is crop out empty space in the pictures before you upload them.

The same can't be said about a lot of other shop software, which will stretch your images out of proportion unless you scale them beforehand. Manipulating images is the most time consuming job in adding products to your store and with this system there's not a lot of this needed. But a good original is needed for a good end result, so you should have a plan on how you will get these for your store.