What program did you use to create the vector? Also, what (if any) tutorial did you use? You definitely need to add some more layers (detail) of shading to it; on the face, I could only count like 3 or 4. The neck having only 2 main colors, that aren't close to the face colors at all, don't look good together, as well as the shading you did with the nose. You need to put a LOT more detail into the eyes, lips, and hair, they can't all be 1 or a few shades. But don't freak out over this, it is only your 3rd, and I'm sure you'll get much better. Keep it up bro.