hi steven,
maybe check a simple curves and levels tutorial first. for example
https://www.youtube.com/watch?v=WnPII6YdVBc
applying flats i think make the biggest improvement to images (and ease in processing). it removes unnatural light gradients you WILL get (as well as dust motes). can sometimes avoid it in narrowband images.
You can create an artificial flat (if you forget to take flats) with things like galaxies or small objects. i did a bit of a method
https://www.youtube.com/watch?v=GW67PwUP8Ww if you want to check it out - it was just to show the process, no commentary.