At least 16 MB
Raw if possible
Closets eye to camera should be in focus
The shoot is square (or keep in mind that a square crop will be applied)
Above in Detail
I recommend a 20-megapixel image although I can upscale a 16-megapixel image. If you can only shoot in JPEG then give me that. Most images with a camera out of the box will be JPEG. If your camera can shoot in a RAW format then give me thatThis is often a rectangle on an LCD screen or a dot in a viewfinder. It may be set to select what to focus on for you by default. Change this so that you can control it with at is in focus and sharp. Point at the eye lock the focus and recompose. Know that the image will be cropped to square mostly. If you are not shooting square images then you will need to pre-visualize what it will look like in his format. If you can visualize the image do so.