Hey Cute,
You've definitely got a lot of potential.
One thing I notice is that you tend to do a lot better with anime and game characters when when it comes to working with images of people, you struggle a little.
That's perfectly NORMAL! A lot of designers struggle with using real people in designs. =)
Here are a couple of tips for you
Avoid putting effects over your focal.
Here you have one little sparkle on her face, and that one sparkle is enough to throw the whole signature off. That's the only thing that I can focus on! Try to avoid effects on the focal. Sometimes a few effects on the body or hands work in some rare cases, but NEVER on the face. =)
Try to keep your focal proportionate when you resize it.
As Radio already said, her face is long now. It makes her look a little funny and when you first look at it, you can definitely see that something is off. Make sure that you have holding down the, "Shift" key when you are resizing so it doesn't stretch funny.
Also, using that same signature, make sure to watch your coloring. You did some short of effect to that signature to make her look like she's coming down from pink eye! Make sure the whites of human eyes stay white and don't get discolored. Also a good thing to keep skin tones natural and not like blue or green. (Not that you used blue or green! Just for future reference)
Try to avoid a lot of empty space
Here you have your focal, but then you have a lot of empty space around her. I would suggest adding some C4ds or fractals to fill the void.
(Also, the thick white border around her doesn't help blend her in at all. At the end of the day, you want your focal blended into your artwork. The border is very distracting.)
Here is a pretty cool tutorial that you can try. Although i'd suggest using your Rule-Of-Thirds when you place your focal. =)
http://photoshopmiraj.deviantart.com/art/Passion-Signature-Tutorial-161812880