Invest in a clip-on iPhone lens or a polarizer filter that you can find on Amazon or any photography equipment shop. Clip-on lenses or polarizer filters are especially helpful if you’re taking photos of a framed artwork. They can reduce the light reflected by the glass or plastic cover.
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).