hey, Welcome aboard, what a nice way to come in here with such a nice drawing... have you been drawing a lot before this?
portraits are a really hard thing to do! so congrats for what you acheived!
you probably know all this, but here are a few things i saw on your drawings:
1. would be somewhat of ideal tight curve to start from...
2. is a rounder jaw line, having a square jaw like the one you made is very masculin, while a rounder/smoother jaw line is more feminin
it's not because you draw portraits, that you should forget about perspective!
if you look at the nose, you can see it's sightly out of angle and don't get me wrong, because that nose is very well drawn, but rotating it a bit to the left could help.
where are your construction lines?
You should alway, and by that i mean ALWAYS strart with theses to get the persp/proportions right. Otherwise you get caught up with detail straight away and in the end, it doesn't always look the way you want it too...
hope this helps