One caveat I would warn about is the difference between how it seems to you you're pronouncing a sound, and how it actually sounds to other people. I started working on my German pronunciation quite recently, by recording myself reading stuff, and found that even though it felt right, my "r"s were actually pretty unconvincing (and I'm saying that as a native Russian speaker - a language that is kind of notorious for its hard "r"s - although they're very different from Germanic "r"s). And sometimes Germans like to overemphasize their "r"s (or it just comes out that way), in a way that I can only describe by comparing it to the Spanish "rr" (or beginning "r"), which is a... thing you (the general, not you in particular) probably should train one hour a day for best results.