I find that posing is ok and cropping is good considering is a self portrait.
By using your on camera flash and your lens near its wider setting , you have created a somehow flat portrait that looks like a snapshot.
your shutter speed reads half a second (I cannot guess why is set so low , maybe the camera is set on night mode?) and even with an aperture of f:8 , slow shutter speed may be the reason for loosing detail , due to movement.
Lastly the dark patches on your shirt draw the eye of someone looking at your portrait away from you face.
Next time , if possible, get a bit away from the background , use a longer focal setting , avoid on camera flash and try to use natural light (Window light ?)