Hi Antonio,
Spontaneity is a wonderful thing in photography, and it is often at the heart of some of my favourite work. What I have learnt over the years is that the faster you can work, the less time the subject has to get to self-conscious about how they will look in a photograph. As a result the photographs are often more compelling.
The photograph of your son has worked out very well, and although I am not too fussed about the overall sepia effect, I like everything else about the photograph including the composition.
Now if there is one thing I would like to change about this photograph it is the catch lights in the eyes. One catch light is good, but two catch lights can be rather distracting. With that in mind, I would be inclined to get rid of the catch light in the upper edge of Joshua’s left eye (in the right as we look at it). With that catch light gone we can focus on his eyes with fewer distractions.
Now this next adjustment is completely optional and more one of personal taste. I have a hunch that Joshua is wearing braces. In the example below I have got rid of the highlights between the lips with the spot healing brush and used Photoshop's Liquefy tool to adjust the lips slightly.
Cheers for now, Anthony.
Image Doctor's edited version
