On Thursdays, we answer your questions!
There is a quick way of creating low poly art found in the Filters Gallery, under Artistic Filters called Cutout. In here you’ll find three controls: Number of Levels, Edge Simplicity and Edge Fidelity. The Number of Levels dictates how many different tones and colours are in the cutout; Edge Simplicity dictates the complexity of the shapes; and Edge Fidelity increases or decreases edge smoothness. Play about with all three sliders!