Here my 2 cents:
I’d skip the ones like “persona” or “forma” because they are almost identical in English and Spanish, and reserve the mnemonics for the ones that need to be derived.
Using a French example for Wednesday = Mercredi:
Click on the sound button to let the French voice speak the words for you. There is only a slight difference in the pronunciation, so you can now use “sea” and “credit” to reason that you need to get a credit from the bank if you want to buy a house by the sea. (Plus you learnt two new words.)
So much for the French translation itself; and Wednesday understood as “wetness day” then nicely links “mer crédit” back to “wetness” because the “sea” (mer) is “wet”; so it can’t be any other day (the two are now logically connected).
Similar to your reasoning for “pais” in the list but both words here are derived by splitting the original word, so it’s more self-contained in that way, plus the reference back to the English word by means of the “wet sea”.
Hope that example makes sense… that’s what I mean by derived.
I’d also cross-reference false friends or words with different endings that might lead to confusion. For example, “caso”, “casa”, etc. Words with -o (usually being a male ending) and -a (usually being a female ending). Now image a couple arguing:
She tells him that it’s the “case” that he (-o) always goes out with his friends and she (-a) has to stay in the “house” with the kids. This helps distinguish the two similar words by having one combined mnemonic rather than to separate ones.
Or since you already referenced Casablanca and in case you are familiar with the line in the movie “Of All The Gin Joints In All The Towns In All The World, She Walks Into Mine.” It is Rick (-o) stating the “case” that Ilsa (-a) walked into his “house”.
I’d always go for [Concrete images] over concepts or (il-)logical reasoning if it can be avoided. Your example of “fin” fits this nicely and my Wetness-day example above really doesn’t.
The above can be fixed by simply adding a Camel. They can walk miles without water which is “incroyable” (incredible), you could almost say “mercredi-able” (not a real word), but now I got a picture of the “Mercidiable Camel”… obviously, the camel refers to Wednesday as hump day.
It’d do the same with “lugar” in your list. If you google “Lex Luger” (not “e” instead of “a” in the name) you’ll find a professional wrestler from he 90s. Wrestlers usually put their opponents into a finishing move to end the match. I.e., a “place, position” to finish the match. In the “sounds like” scenario I find that (“Luger”) a bit closer to the original “lugar” than “luggage” and it creates a more unique image than in the list (…to me at least.)
Maybe check also some other languages that have “image logic” built in as a concept. Here for example the Chinese for “female” and “child”, which put together as two characters means “woman” and combined into one character means “good”:
You can also google “father” in Hebrew which is a combination of the first two letters of the alphabet; aleph and beth (i.e., A and B). Beth means “house” and aleph is derived from a hieroglyph representing an “ox” (or “strength”), so the “father” is the “strength of the house”.
Long post… so, last one: Mano
I’d argue the standard mnemonic here is “Manuela Soledad Palma”; at least everyone I know uses that. Here a link to the meme:
The meme itself doesn’t really say much more than the mnemonic itself, but the explanation is here when you scroll down the page to “M”:
I’m giving a TMI warning; however, this is very common slang in Spanish: