Many of the more conceptual ideas, particularly similar ones, get me. So lots of words with き 気、かん 感、じょう 情 and そう 想 are annoying me at the moment.
Previous/future days/years are also annoying apart from the obvious ones.
I’ve also manage to put “talented person” instead of “master” for 名人 on way too many occasions 
Kodansha has the “brush” radical as “writing brush” and “big bird” as “stretch” meaning an architect stretching with their brush to create a plan for a “build-ing”. My mate “ken” also happens to be a builder. How’s that?
こそすれ is a strange grammar point 
I forgot…
I remember this reading because I has a crush on a French boy called Niko. Easy to associate him with sunlight. Perhaps you can think of my crush to help you remembering 日光。
Kunyomi appears less frequently in the vocab lists. for every kanji, we spent about three days reviewing onyomi. after it’s gurued, we learn several jukugo which use onyomi, then one or two Kunyomi items. A lot more time is spent with onyomi.
Noooo!!! Why’d you do this to me?
Sorry! You’re stuck with this forever now.
I’ll let you know how it goes. Next time I review it is in 2 months to burn it…
Mine’s not nearly as bad.
How did you get the reading wrong twice?
I probably typed たいき because of 平ら.
My worst one. Apparently.
Breath 息
Is it the vocab or the Kanji? And how did you find it?
定款 is problematic, but probably not a very important word because I don’t even know it in my native language. It just feels frustrating to always get it wrong.
Duh, of course (silly me)
予想 has 13 "wrong"s in my leech detector, but it’s not a problem anymore. Yay Leech-Squashing.
transitive versus intransitive verbs: I understand the concept. When faced with the choice in a WaniKani review I have a 50:50 chance of getting it right. mnemonics are the only way to help me out of this.
Words which have the meaning “expectation” and/or “anticipation” are driving me nuts.
One little trick to using が that I found helpful was something mentioned in Tae Kim’s Guide to Learning Japanese. Rather than thinking of が as simply the “subject” particle, think of it as the “identifier.” For some reason, that really made it click for me.