One thing you have going for you when learning vocabulary with kanji is the fact that you can use the primary meanings of the component kanji to form a sort of mnemonic for remembering the meaning of the whole word. This is basically how WaniKani teaches you vocabulary words, after all.
However, there exists vocabulary that either 1) is more commonly seen in kana despite having a kanji version (like for example ある vs. 有る or たくさん vs. 沢山) or 2) just doesn’t have a kanji version at all. Since in this case the word would just be a string of kana instead of unique pictograms that have some sort of assigned meaning to them, is there any way to make memorizing kana-only words easier? Or is it just one of those things where you just have to keep seeing the words being used until their meaning is just drilled into your head?