The Common European Framework of Reference for Languages
Anyone who might be thinking about moving to continental Europe or getting a job there will need to be thinking about the Common European Framework of Reference for Languages, or CEFR for short. Your language proficiency is assessed at one of six levels: from A1 for beginners through C2 for advanced professional proficiency in a language. For an ordinary job, a minimum required level of B1 would be a reasonable expectation; to enter a university, B2 is more realistic.
Flashcards will really move you along at all these stages.
Obviously, to get started in a language, you need words and phrases. First, individual vocabulary words give you the very first level of communicative competency; you can just say "WC?" (vay-tsay) and get your point across, even if you don't know how to say "Would you be able to tell me where the toilet is, please?" Flashcards for individual vocabulary items also help you learn the noun genders as you go along, which is a much better idea than thinking that it'll be easy to just get back to them later (lesson learned from bitter experience...). Secondly, fixed phrases and short sentences are also useful to memorize right from the beginning. Before you start learning grammatical rules, memorized words and phrases not only help you to make yourself understood, but also help you to set yourself a foundation for later grammar learning. Even though you might not understand the grammar when you first memorize a sentence, you give yourself a storehouse of "aha!" moments that you'll appreciate when you later learn the relevant grammar.
After you do this for a while, you will pick up some basic patterns with a small set of words, and be able to insert the right word into the right pattern for the right situation. At this point, Level A1 is within reach. Reaching level A1 means being able to communicate on-the-fly, beyond merely memorized phrases. So you'll need some basic sentence frames, along with a variety of words with which you can fill slots in those frames. The A1 test also involves listening comprehension and speaking, so if you want to prepare for the test, you'll want native-speaker audio in your flashcards. There are many sample tests on line, so you can get an idea of the kinds of material that would be most helpful. Here is an excerpt from the official documents about the kind of areas you will be expected to be able to communicate in: "interact in a simple way; ask and answer simple questions about themselves, where they live, people they know, and things they have; initiate and respond to simple statements in areas of immediate need or on very familiar topics."
At Level A2, being able to function in basic everyday situations is the key target. So, you need to learn the vocabulary words in those areas. To quote the CEFR documentation, you will be expected to be able to: "use simple everyday polite forms of greeting and address; greet people, ask how they are and react to news; handle very short social exchanges; ask and answer questions about what they do at work and in free time; make and respond to invitations; discuss what to do, where to go and make arrangements to meet; make and accept offers; ... make simple transactions in shops, post offices or banks; get simple information about travel; use public transport: buses, trains, and taxis, ask for basic information, ask and give directions, and buy tickets; ask for and provide everyday goods and services."
At Level A2 you also begin systematically learning about an essential aspect of German grammar, namely case: nominative, accusative, dative, and genitive. You really need a good variety of vocabulary words of different genders, to practice switching from case to case.
Achieving B1 is a significant achievement, and requires knowing all the basic grammatical structures of German. Language acquisition research shows that making progress in grammar is greatly assisted by having enough vocabulary so that you can practice lots of different sentences with the same grammatical pattern. This helps you leverage the phrases and sentences that you have memorized, so that you develop the ability to generate new sentences fluently to express your own ideas. At this point, you will be expected to be able to give your thoughts about the past, present, and future, and to give reasons for your thoughts.
After you have reached B1, the next stage involves gradual cumulative learning that is sometimes called the "intermediate plateau." Part of the reason that this is a slow but steady stage is that growing your vocabulary is what has to happen next on the path to fluency. Thus, one of the primary determinants of successfully passing from level B1 to B2 is the extent to which one broadens one's vocabulary, along with an understanding of how words are used in context. Level B2 is also the point at which avoiding gender and verb form errors becomes important - and the point at which you will wish you learned your noun genders and your verb forms from the beginning, because going back and re-learning all your early vocabulary this time with genders and past-participles attached is a real drag. If you can add past-participles to your flashcards' notes, it absolutely is worthwhile.
Getting to the skill level to pass the Level C1 and C2 tests requires developing professional proficiency in your field. So what vocabulary you learn will depend on what you plan to do with your language. They also require sensitivity to style and the social side of language use. Real texts and real interactions are essential at this level. Level C1 marks being able to use the language without difficulty, while C2 involves an advanced, educated use of language, beyond the skills of the "average" native-speaker.
CEFR tests in German are produced by TELC and by the Goethe Institute. Both of these organizations offer sample tests. TELC has a bit more practical information on their website: http://www.telc.net/en/what-telc-offers/german/. For B1, they even offer a vocabulary list embedded in the "learning objectives" document within their "practice material" section. The downside is that the most useful materials, i.e., the learning objective documents, are in German. We hope you find the summary here useful -- if you do, please let us know, so we can do more along these lines!
A comprehensive document describing the CEFR in detail is at
Wikipedia has a briefer but still useful exposition.