Roxy,
I think you're doing very well. How long have you been drawing for?
I've taken many many life drawing classes with both good and bad teachers, and I find that these excercises really helped me with portraits:
blind contour: Most people I know hate it, but it really helps you if you observe your subject and draw without looking away from the said subject too much. I find that the key to getting a likeness down is to stare more at your subject than the paper. If I look at my actual drawing too much, I tend to transcribe whatever I see in my head instead of what is actually sitting in front of me, (which makes for an awesome character, btw).
After drawing for many years, you can eventually learn to "eyeball" proportions, kind of like how a really good chef eyeballs ingredients...but this can still lead to fuck ups.
I've done it...a lot, so It is helpful to measure proportions with your pencil..it is much harder to use a thumb.
When you're first starting your portrait, use vine charcoal to jot down light marks representing where the eyes, bottom of nose and mouth line are, then check your proportions before you completely go nuts with your pencil, charcoal, etc (I probably fail to do this half the time, then I realize that things look off when I'm almost done
)
Also, step back from your drawing often, and/or look at it upside-down...sounds weird, but it helps when you're drawing from a photograph.
ALSO - try drawing with soft charcoal and smudge tool - I found that it helped me a lot
See ya...I have to go back to work
