You are super good and i like the way you draw. Do more.
Edit: Ok i see that you asked for advice on how to draw girls. I found a toutorial on some other site and saved it ( NOTE THIS IS NOT MINE I give full credit to who evers it is. ) ok here it is.
few tips to drawing females. First:Regardless as to what you think, we are created and formed in many different ways. Women have more body fat, and we all have different amounts that give us a unique shape.
I didn't choose a particular style for these women. Just the gist of a gal.
The first is your AVERAGE girl. Not a supermodel, not a skinny brat, but an active, slim teen. This is the normal build of a female. Note that the wrists is always aligned with the crotch. The length of the arm, from the shoulder to the elbow, and the elbow the wrist are the same. But the length of the leg, from the waist the knee, from the knee to the ankle are slightly longer than the arm sections. The Body itself should be slightly wider than the head.
Vuluptuous: This is what you arrogant men might call a "fatty", but this is how real women are meant to look. With curves and all! Much of a female's body fat is stored in the breast, legs and hips, to make room for childbearing.
Fantasy:This is how men WANT women to look all the time. Strong, healthy,beautiful, and with huge YA-YAs. That's fantasy cuz most of the time, that's not possible. Ever see the miss-strong contest? Those ripped women have no boobs. They don't have any because they work out so much that all their body fat is used up, and boobs are just fat, so they shrink away. Models who are really skinny, and have huge tops, usually paid for thier breasts.
WHAT I SEE: This is what I see you guys drawing us as. You try to go for a sexy,tomboy thing, but it just doesn't work if you don't know what your doing(it's like sex!).You have to understand the elements of what makes a woman sexy. Remember,boobs are not just stuck on us. Our bodies are specially designed differently than males to cope with the curves.
Look at that lower chest and the board next to it. That's what some men seem to think. We don't have male bodies with vaginas and boobs added on.Notice the frame work:How the ribs and muscles come up and around the breasts.
Oh yeah, that "OR" is another example of what's not right. Hope this helps