2,000 most common words
Words are the building blocks of a language. The more you know, the better you are at the language.
Vocabulary in language follows a power law. That's a fancy way of saying that, once you know the first 2,000 words, you will know most of the words in most of the sentences.
Be careful. This doesn't mean you will understand most sentences. The remaining words will carry most of the meaning. But it does mean that once you've learned the core vocabulary, you will only be looking up one to three words in a sentence as opposed to every word in the sentence.
With the help of Anki, you should be able to comfortably introduce 12 new words a day, with the expectation to remember about 10 of them.
Learning the first words in any language is a memory game. Expect to forget. If you find a word doesn't stick after several days of seeing it in Anki, suspend it. If you have to make the trade-off between getting a hard word or memorizing two easy words, always go for two easy words.