Hey there! Most DnD Dungeon Master books is a good place to start for building good dungeons. It’s pretty easy to adapt them into a CYOA story format.
I think the biggest problem with starting a CYOA story is dealing with the different choices. I don’t have any books, but this site and this example tree helped a ton when I first started turning Monarch of Witches from a linear story into a non-linear one:
I highly recommend starting by planning out what endings you want to make possible for your players. Then, later on you can expand on everything in between the start and those ends. It helps keeping your story organized and keep you from writing off into endless tangents. Hope this helps!