I think the main issue is the depth and contrast. You can solve this by using different kind of pencils, for exemple: 2H=sketching, HB=main pencil, 4B=dark areas.
Personally I think using a grid is easier to get the right proportion. I make a grid as follows:
1: open publisher and choose the right format of your drawing.
2: scan the picture you would like to use as a reference.
3: open the picture in publisher.
4: put a grid over it (you can choose the measurements of a grid block yourself).
5: draw the same grid with a hard pencil (light) on your paper.
6: you can draw the outlines easily on the paper.
This way the proportions are right. (place of the eyes, place of the mouth, form of the head etc.)
I hope this helps. I think you can be a great artist if you just start with improving these things. It is possible you won't succeed immediately, but it will improve your skills