I can't see any technical mistakes (which is a worthy thing), and you've got the lights so as to show the shadows of the bone structure nicely, so you are really in the zone of "Do I like this photo?", and it's you and the sitter's liking of the photo (or is it a self portrait?) which are the most important things.

Possible things to change if they don't appeal to you (but you may like them):

• You've reflected light in the eyes - do you want them at all, and/or in those positions
• The sunglasses are slightly off-centre - are you happy with how they balance the image (you may well like how they balance the pocket)
• There's wisps of hair on the forehead - but that could easily be because that's how the sitter expects to be (a model would be furious, but that's not what this portrait is of!)
• The hair just fades into the background - which is a valid choice, but did you consider alternatives, such as a minor amount of backlighting?

You look like my old friend Randy from church.