Well, the best is to try different things by yourself, there are tons of tutorials and videos available. Also spend some time on the qnap forums (forum.qnap.com) and on the /r/selfhosted community - these are good sources of ideas.
In terms of books, I did not know there were books specifically on Qnap but out of curiority I checked on Amazon and indeed there is such a book: https://www.amazon.fr/QNAP-NAS-Setup-Guide-English-ebook/dp/B00K7DYYCK it seems very comprehensive and has been upadated in August 2022 !