Measuring Ear Length
To ensure a correct measurement for ear length, measure INSIDE the ear from the top of the inner ear lobe (circled in red on the image) to the tip of the ear.
Measuring Head Width
When measuring the head width for brace sizing, you are measuring the distance between the two cheeks (marked with red x's on the image).
An easy way to do this is to hold two pencils straight while pressed on the cheeks, and measure the distance between the two pencils as shown in the last image.