Check critical proportions and locations while using "transparent mode", which creates a virtual projection onto your work surface.
Simplify your subject into its basic value patterns. Train your eye to see the lights and darks before you get into the detail of color and modeling.
Throughout the history of art, artists have searched for ways to produce their work more quickly and more accurately. Research has been written that argues that even the old masters - people like Rembrandt, Vermeer and Caravaggio likely used innovations like the camera lucida and camera obscura. Artist's Eye re-imagine's these devices using the power of modern technology!