When choosing a wig for your face-shape, all the experts tell you to pull your hair back off your face and trace you face in a mirror with a lipstick. I imagine the latter quite hard to do, but using a ahair-band to pull the hair back is a good idea. Look at your face, and do you see the basic round, long heart shape etc.
One thing I will say having studied faces and heads for fifty years now; anyone over eighteen should never have a direct middle-parting as this accentuates the nose, making it look larger. It also brings attention to eyes that may have a drop to one side.
Another big mistake is; where wigs are bought and the fringe is too long and pulled across like curtains, the look of the piece can be ruined. A simple light trim is usually all it needs, but don’t do this yourself. A hairdresser with experience of wigs is needed to do this properly.