This is my starting point for processing night sky photos in Lightroom. This uses a cooler white balance and more noise reduction than my daytime preset. From this starting point I generally set the white/black points either with the white/black sliders or the point curve. I then adjust the highlights and shadows to taste and proceed from there.
Once you download this file, here's how to install:
1) Open Lightroom
2) Go Edit∙Preferences and select the "Presets" tab
3) Click on the button titled "Show Lightroom Presets Folder"
4) In the window that opens, double click on the "Lightroom" folder
5) Now double click on "Develop Presets"
6) Copy the downloaded file into the "User Presets" sub-folder, or any other preset folder you like
7) Restart Lightroom
It should now show up as a develop preset!