I can see what you're going for! The first thing you should practice is the proportions of the face.
Generally, there are spaces on the sides of the face that are about as long as the length of the eyes. It's hard to explain, so here's a chart to help:
See how on both models there's a space between the eyes and the side of the face that's about as long as one of the eyes? That's how it usually works on a realistic face.
Of course, with the style you're going for, there's room to play around with that, but for now you should probably stick to the vanilla proportions until you're confident enough to mess around with them.
Also, like someone said earlier, you should make the head smaller or the torso larger. The fabric can also be worked on to have more realistic shapes and folds, but I think the anatomy is more important right now.
(here's something to help with the fabric if you're interested)
You might wanna work on the breasts. They aren't supposed to sag like that.
Actually, some breasts do sag like that, I think it's just the way they're drawn that's throwing you off.
When you do your next drawing, try making the bottom of the breasts less prominent. With most clothing that form doesn't show up, and it can be rather jarring if you pronounce it.