Hi!
I've 3 years experience in retouch fashion with Photoshop.
In your project, I know the tools to change background color to make it black, I can use many tools and plugins to make solid background and retouch model's skin (dust&scratch, noise, portraiture, patch...) and retain tattoos. I also noticed the dust on the shirt and the skin under the model's arm...
I have tried the image you attached, if you are interested please contact me, I will show you
Thanks for read!
Sorry my bad English!