The Minert book is very good, especially since it is directed to English speakers looking into the kind of archival material you have access to. The most common name for this script is "Kurrent." Some times, German sources call it simply "Deutsche Schrift." Both terms might help you in Internet searching.

The Gladt book is in German. If you can find it in a library, it shows documents through the centuries, with a transcription and comments.

You know how old handwriting looks "old" to us, even though the basic letterforms are about the same. In the same way, Kurrent changed its look through the decades, so that a document from 1800 and one from 1900 will seem to look quite different. This is just something to be prepared for. You could even make yourself a key ( a chart of equivalents) of the 1800 handwriting -- and be prepared to do so again for the newer one. You'll find guides to penmanship online, where the letters are formed very precisely--also be prepared for actual written documents to be, shall we say, different from the models.

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Minert, Roger. Deciphering German Handwriting in Documents. GRT Publications, Provo, UT. 2013 (2nd ed.)

Gladt: Deutsche Schriftfibel. Graz, 1976.

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LATER EDIT: There's also a fairly active community at https://www.reddit.com/r/Kurrent/ . This has the advantage that you can compare the original Kurrent document, and a transcription, and learn a few things that way. Best of luck!

Practice, practice, practice. It helps if you can find something where you can see the original writing but also have a modern transcription. A guide can also be helpful if there are common (or not so common) abbreviations in use.

As my paleography prof would say: it's about experience and looking.