Good work on your first real venture into the dark and arcane world of figures.
Interesting use of dirt on his face. I'd carry it over to the white straps. They tend to stand out.
His eyes, the bane of face painting, could use some work. His left eye is looking straight ahead but his right eye is looking to the left. A good way to test eyes while painting is to look at the face in a mirror. It was explained to me that doing this is the same as a barber cutting your hair while looking in the mirror, rather than right at you. Also, the left eye could use a bigger iris. It looks like he's a bit bug eyed. Under normal conditions, the eyelid covers about a quarter to a third of the iris.
Don't 'be afraid to punch up your highlights. (I'm still a bit timid there, too.I was just taken to task by a major painter for that this last weekend.) )
The wash could use some more blending on his shoulders. For shadows on green, try adding some red to the mix. I know it sounds weird, but it works. This is part of what's called color theory, which includes shading with complimentary colors.