I noticed that online resources for German seem to be a lot more numerous than for some other languages, but the amount of actual useful content isn't much larger, and its drowned out by a sea of surface level shit. So, I'm going to post the useful resources I find here.
This post is primarily about zero-article usage, which was a lot harder to find information about for German than it was when I learned Spanish. PDF related is a research paper comparing English and German article usage, specifically contrasting usage of the zero, indefinite, and definite articles in both languages in various contexts. The link below is a more digestible Stack Exchange German thread. The OP is asking about exceptions to a common (wrong) rule parroted about when to use the zero article, and the second answer (the one that isn't checked) gives a good relatively short and accurate summary of the actual rules.