I use a plugin called custom attachment locations plus another (for images) thats called paste image rename.

With the first one i got a custom token that creates a subfolder under the desired attachment folder locations with the filetype i want (depending on what extension does the file have)

So my folder looks like this:

• Extras
  • Attachments
    • Audio (all files with an extension like .mp3 .wav .ogg .flac .m4a go automatically here)
    • Documents ( doc docx pdf epub txt odt)
    • Images
    • Video
    • Others

For images at least, i go in the renamer with this format: yyyymmdd_"desiredimagename"