Lesson 10 on N4 has several variations on ‘to do’ and ‘to be’ for polite speech. I’m completely lost as to when which one is used and am struggling to answer any of the questions. Help!
What’s the difference between humble and honorific? That seems to be the hint on the questions.
Humble vs Honorific:
So here’s the difference between お～する and お～になる:
| word | humble | honorific |
|---|---|---|
| 待つ | お待ちする | お待ちになる |
| to wait | I will wait | someone else will wait |
| 用意する | ご用意する | ご用意になる |
| to prepare | I will prepare | someone else will prepare |
And the difference between いたす and なさる:
| word | humble | honorific |
|---|---|---|
| する | いたす | なさる |
| to do | I will do | someone else will do |
| 用意する | 用意いたす | 用意なさる |
| to prepare | I will prepare | someone else will prepare |
Okay, now for お～になる vs なさる and お～する vs いたす:
From my understanding, they basically have the same meaning as their counterparts, just one is more old fashioned or humble than the other.
In other words:
It’s definitely confusing, it took me a while before it all clicked in my head. Hopefully this helps!
Edit: I want to clarify that I’m still a beginner at humble/honorific Japanese and I got all this info from Bunpro (this is just a condensed version of what they say across multiple grammar points). If I made any mistakes here please let me know!
This is a great summary! 
thank you that really helps and is a lot better than my scribbled notes.
It’s difficult when there are multiple grammar points on similar items.
That was a wonderful comparison. Thank you!
Would love to have this specific post be an ‘external resource’ for both grammar points! @Asher
So should お~になる and なさる, お~する and いたす be interchangeable？ I’m finding that there are so many variations on the endings in the questions that it’s difficult to use them interchangeably. I’m getting frustrated. 
Thanks so much for this! It is kind of frustrating when I get a question wrong for using お～になる instead of なさる and vice-versa.
Great summaries! It is very helpful.
I would add something about when one should use humble or honorific japanese.
Humble honorific is used when talking about yourself or your actions as you said but also about people of your inner circle (family, colleagues, friends,…) to someone outside from this circle.
Inside your circle you can use honorific also if you are talking about people deemed ‘higher’ than you, such as elderlies, your boss and so on.
For instance when talking to a customer about your boss you must use humble japanese. But when talking about your boss to a colleague you must use honorific japanese because everybody is from your inner circle so you must take into account peoples’ ‘rank’ (relative to you).
Oh yeah I always forget that this applies for people within your inner circle too. And I had no idea that the way you talked about your boss changed from honorific to humble depending on who you’re talking to. This is a great explanation!
they are my eternal ghosts now 
confuse them all the time.
Great summary, thanks a lot