i think it looks nice so far, especially for your second try and especially since you don't seem to be referring to a model. (did the image come from inside your head?)
i like the build up of colors in the last image but i really like how vibrant the colors of the towel looked in the first. i think you've probably already seen with watercolor that it's really easy to go from vibrant to muddy; i think that's what makes it so hard and maybe that's where you run into a couple of problems.
you have a really interesting sense of color (the purple on the back of her neck is very soft and almost glows) and i think you could push it more by experimenting with complimentary colors to highlight and shade with.
once piece of advice i have is to work a little faster. it might be beneficial for you, since you're just starting, to have traced this woman onto several papers and just do several quick studies. and i mean very quick, like a couple of minutes each. i think you'll find that it might be easier to define mass with just a couple of strokes of color.
and as far as watercolor, i think this is a really awesome example and i've found it inspirational many times so i hope you do to:
http://www.flickr.com/photos/onnder/set ... 170399757/
