I am just going to make this short, and not a novel.
My feet start to hurt really badly from just standing. I know that is natural, but is there any way for me to last longer without having to rest?
I just started working on my first “real” combo a few hours ago, and I am SUPER proud about it. And I am really afraud that I am going to forget how to do something in that combo. Do people forget overnight how to do their combos overnight? Maybe any way to prevemt this?
Well "I have an Answer for question number 2
I Normaly don’t forget a combo overnight But if your afraid youll forget run through it like 10 or 20 times before you go to bed that should help you remember
2- Record yourself doing the combo or write down an outline on what happens in the conbo
My feet start to hurt if I am throwing for a while barefoot or with socks only. Even if you are throwing in your home, try putting on shoes or at least some slippers or something. That really helps me.
It’s an incredible relief to yoyo on foam mats… I have them lying around because I have young kids, but you could get some even if you don’t. 
Most easily found in primary colours at toy stores (again, for kids) but I’ve seen them at automotive and department stores in gray or blue as well.
Do not stand in one place for a long time. Maybe you could lean to one leg and switch every now and then.
You could either: a. write it down step-by-step, or 2. film a tutorial for yourself.
Hope this helps.
Muscle memory. Do it until your fingers bleed, and you will probably never forget it. That’s all l do to remember tricks.
Name the trick. Do the trick consistently for 10 mins. Pray to God you don’t forget it.
Came in here to say this. Can’t imagine getting sore feet from yoyoing unless people are standing and throwing for 4+ hours. Getting sore feet just from standing up to play with a toy for a short period of time is far from “natural”