For simple works (basically those that are not acrylic or oils and do not have any embellishments or three dimensional aspect to them) you will actually usually get a better result through scanning than photography. You’ll get much more resolution, and a more evenly lit and predictable result.
What Sells Best On Shutterstock?
Some types of photos that sell best are Portrait Photography, Food Photography, Landscapes (usually with people) and fine art photography (artsy).