Good effort Elson. It is really hard to get everything convincing but I think you have had a good "innings" and had fun doing it. I have nothing different to say other than give you encouragement that I think you are on the right track. I say this coz I like your chunky manner to the drawing presented here and may be it could be something you could exploit. If I could be so bold and may be check the proportions in between the nose and chin? I only say this as this is also an area I have to practise with.

Hey Elson, good job on this. You're definitely understanding the concepts, and there's nothing in this drawing that is particularly incorrect. Your thirds are correct enough, the structure is getting there, and the composition seems thought out. What I might say is that the values are not close to dark enough, and your edges/ shapes aren't well defined. This makes the overall drawing look non committal and difficult to read. For example, his cheek feels like it's either extremely scared or misshaped. His hair line isn't well defined, and the mid tone shadows on the side of his head are too dark. Something that would help would be understanding how to break up shadow shapes better. Some people to look at for that sort of thing are @Stephen Bauman, Charles Bargue, and John Vanderpool. I think you're getting there in terms of proportion, and you'd go a long way in improving the appeal of your drawings if you were to be more intentional about your shadow shapes. I've included some images from Charles Bargue and Vanderpool to give an idea of what I'm talking about. Hope this helps!

Good job. You may want to consider going darker with some of your darks, or at least continue learning how to create an interesting artwork that's high key. I think if you managed to get the background more consistent then that would improve it. Here are a couple of good videos on shading on Proko that you may like. https://www.youtube.com/watch?v=-dqGkHWC5IU&t=390s https://www.youtube.com/watch?v=LrHfrncvODQ&t=553s