This kanji right here. Again, and again I have been having problems with this one. The meaning is fine, but the reading is the problem. So, to help me remember that the reading is mata, I am publicly shaming this kanji.
Please join me in shaming this kanji to help me remember. If you don’t, then what’s the mata wif you?
I actually more struggle with the radical which is stool (I keep on thinking it is stand).
SHAME SHAME SHAME (Game of thrones or What We Do In the Shadows reference. take your pick)
Maybe thinking about it in connection to じゃあまた or また明日 or something would help? Though if you aren’t familiar with those phrases then maybe not 
Again and again, nothing 又’s. Again and again, I got it wrong too, but i’ll never get it wrong again.
Except for the time when I wrote まだ instead of また but I won’t do that again.
This is one of the few where the standard mnemonic worked for me just fine
What’s the mataaaaaaaaa
It’s not a kanji I see often but when I do it’s usually a part of 猫又（ねこまた）which is a cat youkai.
Nekomata 
This is precisely how it stuck in my head right away.
I can think of a few ways of remembering this. One of them is a bit rude because it uses a kanji that looks almost exactly the same that can mean ‘groin’, but whose more general meaning is ‘fork/split’ (叉). Both kanji are pronounced また, both low-high in terms of pitch. (It’s how they join to a particle that’s different.) 叉 is already a euphemistic way of referring to certain body parts, so on the bright side, the kanji isn’t all that rude. It’s not necessarily rude anyhow.
However, if you’re not familiar with that kanji or would just feel more confused with yet another similar kanji… well, there’s what @natarin suggested:
If you’ve watched anime or anything with casual conversations involved, you’ve probably heard「またね〜〜」at least once when people say goodbye, so I think this is a pretty good approach. Plus, it’s literally this kanji: you’d write「又ね！」if you wanted to use kanji for this (which is rare).
Some other ideas:
(Sorry to inflict this on you if anime and anime-style games are not your thing. It’s just that this dance came to mind when I had the idea for that mnemonic dance.)
I hope at least some of this is helpful.
I tried so hard and got so far
But in the end it doesn’t even 又
I had to fall to lose it all
But in the end it doesn’t even 又
One thing, I don’t know why
It doesn’t even 又 how hard you try
Keep that in mind, I designed this rhyme
To remind myself how I tried so hard
Lol I keep giving my answer as stool for the kanji. But I know that again is mata. For some reason, the mnemonics for that one works really well for me.
You’re sitting again??? What’s the ma ta with you??
And nothing else 又
I remember this one cause of this VTuber Nekomata Okayu | Virtual YouTuber Wiki | Fandom
Works for me. Although I always forget the stool radical. I usually guess again or stand
I took many hits until I started consistently differentiating the radicals 又 and 文 
I actuall struggle with the meaning for the kanji, I still keep putting stool, stool, over and over again, so SHAME, SHAME!
Coincidentally, i had this kanji showing up today, so it went to the enlightened pile 
The shaming has worked, got this one correct on my review today. Thank you all for the help.
No more am I staring at the kanji thinking:
“What’s wrong…”
“What’s the problem…”
“Issue…”?
No it’s mata!
I thought the maternity chair was absurd enough that it stuck with that mnemonic 
Eh what? Is that mnemonic gone? I thought it was great
午 (noon|ご) is the one which I seem to struggle with as it’s so similar to 牛 (cow|うし)…
It’s not a race though, and eventually they all just seem to click. In particular after a good night’s sleep.
I just came here to shame you, not the Kanji, for not remembering its reading.
Hakuna 又ta.
