Simply put, Paint.NET is one of the best free photo-editing tools out there. It manages to strike a fine balance between the complexity and features of programs like Photoshop and GIMP without being as challenging to grasp. You can use almost any advanced photo-editing features like filters, layers, masks, and curves.
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).