My best advice is to always keep note of the constant theming around a given character or situation, and then expand on it yourself. animals, plants, weather, items, elements, certain words and anything else of note, write it down while reading or watching the media if necessary, even. when you have them, you can create concept maps/topic maps and link what you got with things that they immediately remind you of, or things you can find on the Internet. you can play around with mixing different characters themes for pairings too. The reason I might seem good at it is that I like random trivia a lot, so when I see something about a character, I get really curious and start googling it and anything related, going down a rabbit hole of the given subject. read those beautiful wikipedia pages with 100 notations. i am genuine when I tell you that you can connect anything to your favorite character if you squint enough. Anthropomorphise the hell out of everything

something else i feel like saying is keeping the source media in mind; for example, if a character is from jp media, its likely that any related flowers will primarily reference hanakotoba as opposed to victorian flower language, so you’d be better off researching in the original language, even if you have to use mtl. of course this isn't Always the case, but it is worth considering because you might be missing out on a whole world of symbolism by restricting yourself to english.

and thank you for your praise! im really glad my art can reach people. your admiration means a lot to me:)