1. Smile. You have a blank stare that isn't doing you any favors.
2. Iron your shirt collar. It's a portrait, and isn't the whole purpose of a portrait to show you at your best?
3. Shave. Again... portrait.
4. Your location is just fine, but the sky is blown creating a distraction. I would suggest that next time you kneel down, and frame to eliminate the sky through the canopy.
5. Fill flash to fill in those shadows a bit.
I had a huge rant to go with this, but I will (for the most part) keep my mouth shut. I will give you the short version though:
If you want serious critique of your work, put your best foot forward. Do not include a laundry list of reasons that the image is not good, and then expect people to make the effort to help you out. My first thought was "If you really don't think it's very good, and you made no effort to correct the things you felt were wrong, then why did you post it?"
Post with confidence. Choose the images that you can say "This is the best I can do right now. How can I improve to become even better?" If you can't say that... why post it?
Sorry it's harsh, but I've seen a lot of that lately, and you're receiving the lashing.