Sweet! Quick edit:
I omitted any work on yourself, because I think what I've done gives enough of an idea. The same principles I describe in the following should be applied to that third figure as well:
Be very mindful of angles. The brain tries to orient faces when it sees them to be front, centre, straight. You have to force yourself to see exactly the angle that the head is oriented and take the time to make sure the angles match up in your drawing.
Similar to angles, be mindful of proportions. Compare relative sizes of objects in the subject. You can run imaginary horizontal/vertical lines from landmarks along to other spots in the subject to see where things should line up. For example you can run a horizontal line from the bottom of CJ's nose along to the top of your nose. Things like that help you to line stuff up and get proportions correct across the image.
Consider how all the colours in an area that a single pixel is representing are going to merge when you translate it over to your piece. You can see this at work in my edit of CJ's eye. It's tempting to have a WHOLE PIXEL represent the little spec of white in the eye, but that pixel's job really should be to represent that whole area, so it actually should be much darker.
