Totally agreeing with all of your points.
Actually I'm anything else than a beginner - I had started making music maybe 15yrs ago and my first record was released about 7 yrs ago, but I'm always trying to develop my music, because there is always room for improvement and development.
This actually hasn't to do with mixing, but I'd say a very important point is the ability to discard stuff. I think it's always good to have a healthy rate of wastage. If you discard too many ideas, it is an indicator that you should develop further in the current direction, if you discard too few ideas, you probably should try another direction.
Another point is time and experience. Many people think they just click through a few video-tutorials on Youtube, sit down and make a track. Well that might actually work, but it's nothing you created as there was no real creative process involved. Art needs time, you need to find the one thing within yourself that wants to communicate through music, you need to find your own way (like Loren already posted).
The more experience you have, the more work you already did, the easier it is for you to get things done.
But now back to the mixing topic:
I think for genres like Ambient or other genres of electronic music, the mixing is already an integral part of sound design and maybe also the arrangement. Right now I'm sitting on a new track, not really Ambient to be honest, but something similar (Ambient Dub Techno).
My workflow is/was like that:
1.) Started with sound design for a major chord sound of the track.
2.) Experimented with different chords.
3.) Created a 8-bar loop with the rhythmic chord.
4.) Sound design for a bass drum, which I built upon an older bass drum patch.
5.) Adding another chord sound, I made in a previous, unfinished song and tweak it (EQ, Filter) to fit into the current track.
6.) Creating a hihat from a recording of static noise I recorded previously, creating a drum pattern for it.
7.) Adding some high-pitched effect sound from an unused previous track.
8.) Tweaking the stereo image of those high-pitched sounds.
9.) Adding a bass sound "wuuup" from a previous track, but adjusted with filter and EQ.
10.) Started working on a second chord sound.
11.) Adding another bass sound.
12.) Adding more high-pitched sounds I made from a recording of breaking a pencil (I made this recording years ago...)
13.) Adjusting the chords again. Adding Effects.
14.) Setting up my controllers and perform a live arrangement.
15.) Listening to the live arrangement, deciding to add another chord.
16.) Listening again. The filter of the new chord goes to high.
17.) Listening again.
18.) Listening again.
19.) Listening again.
20.) Listening again. The Hihat is too loud.
21.) Listening again.
22.) Listening again.
23.) Listening again.
24.) Listening again. Adding a cool drone to the beginning I used on my new CD.
25.==now) Listening again
So another point to add:
Listen. Listen. Listen.
Really listen to your music a lot, listen in different states of mind, listen at different times, listen on different equipment, on different volumes, etc...