A well composed shot with good feeling. If you can dial back the flash on the camera, the tone would improve greatly. the "open" shade of a tree works well for portraits, but you want to avoid flat light that is even all around. A good rule is flash that is one stop under the normal light. If you cannot manually control the flash, try a diffuser or use a bit of tissue paper or similar material to "soften" the light from the flash. Keep at it, you are doing great.
It appears you used a flash on this one. I can see a slight line of a shadow on the tree beside his face. A cure for that is to have the model move further away from the background so the shadow will not have anything to fall upon. Maybe if you used a diffuser it would help also. Still too much to remember? lol! keep going you are doing great, before ya know it it will be second nature!
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