The star colours....
I "select" the "colour range" of a few of the smallest stars. Making sure there is a variety of colours, then adjust the "fuzziness" to the right so as most of the stars are selected.
Then I "expand" the selection by 2 pixels and then judiciously boost the saturation across the board. Sometimes I might give the yellow channel an extra boost.
If the DSO in the image, which would have been caught up in the selection process, gets over saturated, then select just the DSO and desaturate the same amount.
Or you can just use Caboni Actions "Increase Star Colour".
