This is how I have mine setup:
Main folder "Karaoke"
In Karaoke I have Subfolders for each manufacturer: "DK", "Chartbuster", "Pop Hits", etc
Then in those folders either directly the Disc-ID as a subfolder, or (if there's a lot of discs) I separate it into for example: LG001-LG100, LG101-LG200... you get the idea and then make Subfolders for each disc.
That's not a must, just how I do it.