I want to learn Spanish. I have a basic vocabulary and understanding. What’s the fastest way forward in your opinion?

"Fluent Forever" has a suggestion of putting a picture (from, say, google image search) on the front of the card, and the foreign word as the answer. That way you test yourself by producing the correct word without translating it from language 1 to language 2.

Example for Spanish:

Front: picture of a "gatito" from google image search. Back: gatito

The word "kitten" is not used at all. No translations!

The reason you search images in the foreign language is that sometimes the foreign word has a different connotation, and isn't a direct translation. (The example he used was for "girl" in Russian. девушка supposedly means "girl" and yet when you search it, it's (mostly) seemingly a certain type, not "girl" in general.)

That only works for simple words. For example when I google for "Zufriedenheit" (satisfaction), I get a picture of a red boat.

What you say makes sense.

In that particular case however, there might be a simple mistake: девушка doesn't mean "girl" in russian - it means "young woman". A "girl" would be девочка.

On AnkiWeb there are a ton of decks available made by other people, including some really high-quality ones for Spanish. I'd recommend you download one of those, and then if there are words/content you're already familiar with, I believe you can go and set that you've already "learned" those words.

Other than Anki, clozemaster and supermemo.com are two good paid options. I'm currently paying for supermemo.com*, and the two decks I'm using for Spanish seem to be pretty good.

Clozemaster uses word frequency lists and sentences. Honestly it's (clozemaster) one of the best free SRS products I've seen for multiple languages.

I'd avoid memrise (too many horrible quality decks). Duolingo isn't bad but certainly isn't comprehensive by any means.

The reason I'm paying for supermemo.com is because it has a good quality Chinese deck and those are hard to come by. I also want to use the updated SRS algos that it uses. SM-2 is really old and does not handle skipped days well at all. The newer versions of the sm algo are much better in that respect.

Note that flash cards have only limited usefulness with learning languages: you can use them to remember grammatical rules at first, then do isolated word-choice tasks and expand the vocabulary. You'll still want to do massive amounts of reading in the target language to absorb the proper word usage, and the grammatical practices will stick better this way.

I recommend https://supercocoapp.com - it’s my app, so I’m biased, but it has great content and one of the few apps that really focuses on listening and speaking.