This is my normal work screen, not that you should copy it, but it should give you somewhere to start.

Most important is the Histogram, I keep it at the top right. All these can be found to start with under Window on the top line. The histogram tells you about the photo, left is dark (black); right is light (white). The Histogram is split into 256 vertical columns, and in each is a vertical line representing the number of pixels found at that shade. Most astrophotographs are heavy with dark background so the histogram will likely be heavy on the left. The stars are likely to show towards the right. Keep an eye on it as you change things while processing.
Below it is a row of three items
Info. I usually only show the top half so I can see the number of pixels of which colour under the cursor on the photo. This depends on the Sample size. To see that click on the eyedropper tool to adjust it from point to 3x3 or 5x5 or a wider square. For background you should be trying to ensure the three colours are almost the same value. I try to get mine to 20,20,24 for red, green and blue. It also helps you find the nebulosity.
Adjustments is a means of making adjustments to the photo in a non-destructive manner, whereas the normal Curves and Levels etc. can be counted as destructive, in that if used their effect is permanent and to remove it you have to go back to a prior History state.
Channels refers to control over individual colour channels.
Below is History, Actions and Layers. Just for my convenience, I can get three items on a line, helps to use less space on the screen.
History is originally set at about 20 steps, which means that when you make the 21st change to your photo the first one is dumped. So I reset History, Edit/Preferences/History States to 200. This allows me to go back to see what I did earlier on.
Actions. I load Noel's Actions and Anne's Actions here, obtained from the internet. They both have to be bought, not costly though, and worth their weight in gold as good shortcuts to doing things.
Layers. Always available to quickly add or adjust layers.


This is a work flow that you can follow in processing an astrophotograph. You can of course, add your own steps or miss out some of these. The actual photograph will dictate your course. It assumes you also have GradX and Noel's Actions in your PS toolbox. Don't overdo any step, be smooth and subtle.

How to do it
Image/Adjustments/Equalise then Crop the edges all round
To see what you have in your photograph. Then turn it off and Crop edges to clean up histogram
Levels and Curves
1. Use levels to move black point to base of histogram
2. Big stretch
3. Contrast stretch
1.  Don’t clip data
2.  Usually only one big stretch (mild for clusters)
3.  Contrast stretch is “S” curve.  Set points on curve for sky and nebulosity.  Pull sky down, nebulosity up.
Soft Colour Gradient Removal
Noel C
Run once
Use for light pollution. 
Gradient Removal
First Run:
1. Lasso DSO, feather 20, invert
2. Check balance background colours
3. Run med/low
Second Run:
1.  Set Magic Wand Tool to tolerance of 35
2.  Click in black area
3.  Use Lasso with Alt key to remove DSO from selection
4.  Run fine/high
First run includes entire image except DSO.
Second run includes only black areas outside the DSO.
Set B & W points
Move black and white sliders to capture spread data across entire histogram. 
Be careful not to clip; sometimes not necessary.  Some actions change histogram so may want to repeat this in later steps.
Local Contrast Enhancement
Noel C
Run action once
Not on clusters
Enhance DSO
Noel C
Run action once
Not on clusters.  This takes a while.
Cosmetic Fixes
Use clone stamp tool or other PS tools
Remove hot pixels, dust, etc.
Increase Saturation
Three options:
1Jay GaBany method
2. Noel’s Increase star colour
3. PS hue/saturation
Run Jay GaBany method as often as needed. It enhances the nebulosity without bringing noise in.
For galaxies, use Noel’s Increase Star colour instead, then PS Hue/Sat, increase saturation by 20 or so
Increase Star Colour
Noel C
Run action one or more times.
Complements previous step
Levels and Curves final
Set contrast with S curve
Check black and whites points also
Noise Reduction
Noise Ninja (but it reduces colour),
Noel C deep space or space noise reduction
Mask out DSO, feather 20, invert
This may change image and require reset of black/white points and image contrast
High Pass sharpen, possibly 2 or 3 times with different radii
Duplicate layer, use HP on the top one, Blending mode – Overlay or less aggressive Softlight.
Less Crunchy more fuzzy
Noel C
Run action once
To taste
Final check
Repeat of steps shown above as needed
Tweak curves, check colour balance, maybe reset white point with eyedropper