Firstly, i only put phrases or full sentences into anki, except if they’re nouns that really don’t require a sentence. a lot of nouns don’t really have much “usage” information, but it still makes me nervous to just put a single word in.
I generally get my sentences from books that i’m reading. Currently i’m reading harry potter #2 in german (”Harry Potter und die Kammer des Schreckens”), and although i understand a lot of it, i constantly come across words that i don’t know. I don’t put every single unknown word into Anki, however. I usually wait until i’ve seen a word more than once, or if there’s a certain paragraph where there were MANY words that i didn’t understand, then i concentrate more on that particular paragraph.
I do this because i put a lot of emphasis on reading without stopping. If there’s a word that continually bothers me, then i’ll use a highlighter to mark it for later, and then go back to it later when i’m working on new anki cards. Sometimes when i go back to it later, it makes perfect sense so i don’t bother.
Combined with this, i sometimes get some cards in anki that just annoy me. Maybe they seem useless now, or maybe i always get them wrong and they just bug me. these get deleted mercilessly. I know i’ll have no problems finding more words to put in anki, so i don’t worry about losing a couple of the stupid ones.
Another thing i’ve been trying lately is using electronic copies of books in order to do some statistical sentence-mining. I use an emacs add-on that a friend wrote, which makes a list of all words that i have in any cards in anki, and then uses that “known” list to find words in my book that are “unknown” and are also of a high frequency. It then gives me example sentences for those words. This way, i can work through the important vocab in frequency order, which helps tremendously.
In general, i try not to focus too much on words i “need” to know. Ya, eventually i want to know EVERY word, but i don’t need to do them all right now. There are plenty of things to learn, and i think i’ll be more effective if i do them in a better order (and usually i think this means frequency order). This is why i try do wait until i’ve seen the word more than once in my paperbacks, or i actually do frequency analysis if i have the electronic form.
Also, remember that you don’t need to worry about how much you know in total so far, you just need to keep increasing. As long as your knowledge keeps going up, you’ll get there. Don’t worry about grabbing everything right now this instant.