A good filename is short enough to scan and specific enough to distinguish from neighboring files. Slug Generator can simplify a title, but inspect the result before using it as a filename.
Remove characters forbidden by your target file system, avoid private names, and preserve a meaningful extension. For shared files, a date or version can help when it follows one consistent convention. Beware that transliterating Unicode may collapse distinct titles into the same slug.
What title and file type are you naming?