Usually, mnemonics are my nuclear option if it gets to this point. I guess one could say I have a sliding scale with my vocab, where I step the word up if it's problematic:
- base word
- base word with sentence
- base word with sentence and meaning note
- base word with sentence, meaning note and/or mnemonic
Here's an example. A while ago, for some reason I constantly mixed up 転ぶ (to fall down/over, pronounced korobu) and 運ぶ. (to carry/transport, pronounced hakobu). hakobu is a very high frequency word, so even seeing/hearing the word wasn't enough. I initially tried a visual mnemonic with the kanji, which didn't stick (and French doesn't have, of course). Eventually I connected the word hako, meaning "box," to hakobu.
hako wo hakobu. Carry a box.
It's been much stickier since, although I still sometimes find myself sometimes briefly pulling up the binary choice and the mnemonic before selecting correctly. The association's still there, but it's faded a lot since I've put in more time with the language.

