If you are going for a head shot, one of the most important tips is to not make the common mistake of over-focusing on the eyes. In a photo, the eyes take up the majority of the photo's frame, and when people are trying for that perfect shot, they often end up over-thinking this. Remember that photos are not made of frames; they are made of images. Therefore, if you want your image to stand out, you need to keep the focus off of the eyes.
Another common mistake that people make in their headshot