This is your sign to never stop trying and practicing. I came back to this portrait one year after. My first attempt looked like this:

Now I see the progress: better color transitions, more natural proportions of the face. 

So even if you are not fully satisfied with your painting, just keep going, and you'll become better with every painting, I promise! 

And here is one of my favorite portraits I've painted last year. Once you learn the basics of painting portraits you can create more complex compositions and add more details.