One key to working with DOS is to understand the file system. This is not just about organizing files, though that is certainly a part of it, but also about keeping your system running smoothly and recovering lost files in some circumstances.

Links:

https://en.wikipedia.org/wiki/File_Allocation_Table

https://en.wikipedia.org/wiki/Disk_sector

https://en.wikipedia.org/wiki/Track_(disk_drive)

https://en.wikipedia.org/wiki/Data_cluster

https://en.wikipedia.org/wiki/File_system_fragmentation

https://en.wikipedia.org/wiki/Root_directory

https://www.ahuka.com/dos-lessons-for-self-study-purposes/dos-lesson-9-the-file-system/