I think you need to improve your shading . it is looking very flat . just focus on shading first

Heya, nice start! I would check your shoulder line and neck area. Perhaps the shoulders are a little low or the neck tapers too much. Also I feel the line of the two shoulders is usually a soft rounded curve whereas yours is curved the other way on one side and is straight on the other. Try and find the whole shape for the shoulders and create a soft 'n' line behind the neck. Hope that makes sense

Hey Valerio, Like Isak said, without the reference its hard to see what you are going for. but, as a general rule, when laying in or blocking in a portrait, its good to separate the shadow side from the light side. Then drop an even tone over the shadow side and dont add any value in the light side yet. This allows you to get the shapes just right before jumping into rendering. It should look something like what I did over your drawing. I hope this was useful :)

Without reference I cannot say what you are aiming at, but it looks like the eyes are too far apart, and I suggest you add some more variety in the values...