OK this is my suggestion for folder / file structure (based on Poser 5 and later for the PC). And you may notice no exclamation marks. !!Please!! LOL

One main thing to point out is that some files can be moved around whilst other files shouldn't. This is because of the file path created withing the library files to load geometries, textures, etc.

Basically the library files are an instruction file to load content (but of coarse they do a bit more than that). And the geometries, textures, etc are the content to be loaded.

For example: Mum wants to make omlet and gives you an instruction to get some eggs from farmer John at No 3 Lanes End. But farmer John has moved. The instructions are no longer valid so mum can't make you an omlet. Sigh!