Don't get too hung up on the technical stuff.
If you don't know what you are doing, it's easy to make a mess of things, while your auto-exposure would get things right most of the time.
The photo you posted wouldn't benefit much from all of that anyway.
The biggest problem with the image is that there is no subject.
It's a whole lot of distant blah.
A good photo needs something to catch the viewers eye and draw it in.
If you'd flown closer to something and composed a photo of that something, it would have had lighting suitable for photography and been a lot more interesting.
To show what I mean, here's an example that you could have shot with autoexposure:
Note that there's a subject and despite low light levels, you can see interesting details that your eye takes in.
Then it can wander across the background.
