Folks here is an image that I did my first EVER attempt at retouching. it is an image of myself when I was a child (obviously) I did this retouch about 6 years ago, and am planning on totally redoing it again soon---
Very nice job, especially considering you had just started out when you did it.
If you want to go a bit further, without a lot of extra work, let me suggest that if you make no more adjustments except nail the whites, blacks, and pure gray tones (ie, as having no color), you will immediately see a major improvement in your image. Correcting these will also help actual colors like the red in the sweater and the boy's face color.
I couldn't resist doing a bit more than that, but just getting those colors right is probably 75% of what you see in the attached image. A good way to do this is to use the black, white and gray eyedroppers in "curves" tool.