I'm only a beginner myself but looks like your on the right road, just need lots more data and you'll be set.
I had a little play with your jpeg and all that really seams to be causing you trouble is the sorting out the background.
The wipe feature in StarTools helps out immensely, make sure you try out that.
Not sure if you like what I have done, but my work flow in StarTools was: Bin the image quite a bit to help out with the noise, then did a wipe to fix gradients and colour cast, then did a little bit of a stretch to brighten things up a bit, then add a bit of contrast and tweak the colour a tad.
