How to get Good Expressions in a Model?

It was nice using my new easel to set up and draw Tim's profile.  I told Tim he could play video games while I drew him, but now I know that was a mistake.  It caused him to have a blank zombie expression and his head was tilted down causing extra flesh under the chin.  I think I will draw him again looking straight ahead.  I liked drawing the detail of his ear.  I think it turned out well.  I need to work on drawing hair.  I got the edge OK, but I wasn't sure what to do with the rest.  I also found his eyebrow difficult.   Well...like I said...I do believe I need to redraw his profile with him looking up.