Hmm... I thought it already was kinda smoothed out... I didn't do any 'extra' skin smoothing, but this was shot on film, which generally requires less skin smoothing than digital (it just comes out that way). Which specific areas are you thinking of? ...I don't want it to look 'plastic'.
Positioning of the arms is very off-standish. Shoulders rolled foward only emphasize this.
Positioning of you key light is suspect. Notice things such as her gullet, her left lapel and left wrist. All seem a bit hot.
Wardrobe malfunction on the right lapel.
Missing right elbow.
Skin smoothing is NOT an issue here.
Nice lighting ratio on her mask, but the Rembrandt pattern is slightly amiss. I think the key light is a little too far to the side of your subject. I would suggest to bring it back towards the camera.
Did you try anything to modify the one light? I have been messing around with portraits too and for a couple bucks, you can get some foam boards from Walmart and really play around with light. I don't want to jack your thread but my last three pics uploaded to Flickr are just that. it's my "Ghetto studio"
As someone mentioned, the positioning of your key light is....well, key. In this case, I'd say that it was too far to your left and not high enough. Look at the shadow of her nose and it falls across her face. The shadow is just getting into her left eye and is going horizontally across her cheek, maybe even up a bit.
By raising the light, and maybe bringing it around to the front, just a bit, you can cause the nose shadow to stop before the eye and to be cast in a downward direction. If you move it high enough, you may even be able to hide that highlight on her lower left cheek, which isn't great.
Also, I think that the photo could have been improved if she had just pushed her chin/head forward (thus tightening the skin on both her neck and face) and tilting her head a little more to her right (accentuating a feminine pose).
Lastly, as mentioned, the highlight on her wrist isn't great.