As an avid German learner, I naturally end up creating lots of notes, tables, memos etc. to refer to later. Among those, I have one that I use way more often than others.

It deals with endings of articles and adjectives in genders and cases:

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I used some textbooks as an inspiration, borrowed examples here and there, put them into a table, rearranged them as it felt suitable, and, importantly, added a few graphical marks representing how I feel about those rules (or perceived absence of rules): there are those “red” zones where the “er” is added, or the black ones ruled by “m”, and the brown “n”-zone, the arrows denoting that the gender feature is “eaten” by the article and is gone from the adjective and so on.

In other words it has become a deeply personalized, and rather useful, tool.

Feel free to use it. And good luck with your learning!