I cannot for the life of me keep all the words for great (or greatly or considerable) straight, and which are tai and which are oo. I can generally get 大きい because it ends with -i and 大きさ by analogy but then there’s:
Ugh. I get the impression this is just a “keep studying” question, but has anyone come up with better mnemonics to differentiate things?
My tip for you would be to try to remember words not by their spelling (aka not by kanji), but by pronunciation aka kana. It works for me that I know the word たいした. Now, if I see 大した, my brain will try to recognize it. おおした? nope, not found, so that’s not it. だいした? nope, that’s not right either… たいした? Oh yeah I know that one. Might be harder further on, when you get different kanji for the same word, like のぼる(上る, 登る, 昇る) but WaniKani doesn’t really help with nuance much anyway so you do need to learn these separately somehow (I google search a lot of these), or when you have different words with different kanji but same pronunciation, like こうえん (公園, 講演), you’ll have to learn that there’s different words that are pronounced the same way, maybe you can make a mnemonic in your head to differentiate between them, I used to do that for a while. But the language is spoken, and when people hear words they hear the kana, not the kanji, so that’s my advice to you, memorize the kana and then in reviews use the kanji to get to the word you already know in kana. Not sure how much it helps, but that’s what works for me.