In reading Fluent Forever. The author makes a point of something I had begun to suspect on my own: Learning to hear and correctly pronounce a language will help you learn much faster, because your brain can make sense of the sounds it hears and you can more directly benefit from reading because you will be able to pronounce whatever you read. German being much more consistent with spelling helps a lot too.
I've tried the whole “record yourself and compare to a native speaker” thing, and that does help quite a bit. But I’m only guessing at how to make those sounds, and kinda stumbling by trial and error before I get it right. As a result, I end up practicing every single word that way, which seems impractical.
I know that choral singers have some sort of methods for this, I just can’t seem to locate a good, rigorous resource.
What I want is a way to learn to form the sounds with my mouth. Now, a number of the books I have include basic pronunciation guides, but these mostly compare the sounds with English sounds (“it's like an e but with your lips rounded...*”). The IPA resources I’ve seen have diagrams and such that seem to indicate something about what to do with your tongue and so forth, but it requires a lot of assumed knowledge to make sense of those diagrams. Once you have learned the sound that goes with an IPA symbol, you then have to learn what letters in German that symbol gets attached to.
Ideally, I would like some resource that shows me with lots of pictures and diagrams exactly what I need to be doing with all the different parts of my mouth, and practice drills to learn to make each sound without thought. What resources are dedicated to learning German phonemes?
Since this keeps getting upvotes, I figured I would update with what I finally found:
Der Kleine Hey (ePub version with embedded videos / book with DVD version / DVD only version), as mentioned in the answer. It is in German, which makes it a bit difficult for a language learner, but what I find most valuable is the example pronunciation texts for each sound, and the example videos of those passages being spoken by professionals. Don't bother getting the text-only version, get the DVDs or enhanced ebook (ePub with embedded videos).
Fluent Forever Pronunciation Trainer was most helpful at helping me memorize the spelling<->pronunciation rules, which makes reading basic German much more helpful. I did not find the minimal-pairs in that set very effective, because you never hear the two pair sounds side-by-side.
The Diction Police Podcast is aimed at professional singers, but I also found it helpful in learning about common mistakes and more nuanced tips. The example texts are read aloud, not sung, so it is still useful for normal folks. You do need to keep in mind that there are differences in sung German vs spoken German, but these are usually explicitly pointed out.