Thank your for posting your art Dennis. I would suggest to chose one of the methods for constructive drawing (be it loomis, or the abstraction) and try to stick to it. It has helped me a ton. If you can watch the free videos Proko has placed here and youtube. One of the most important things is remembering that the features are 3 dementional, I would work on wrapping the eyelids over the eyes.

One thing I'd suggest is using bold, heavy contour lines like the one you used on the right side of the woman's face in the first (left) pic. Since that side of the head is in shadow and closest to us, I'd use a similar line except maybe a little thicker. David Finch has a video about line drawing where he talks about this. Maybe try that out?