Having an IPTC, XMP or any metadata attached to your image, makes it significantly more valuable for search, permissions, and copyright.
The best way to manage IPTC info is using the software program PhotoMechanic on a desktop. Thought Lightroom and other programs are capable of adding basic metadata.
Download KLC fotos Generic IPTC
Pro tip: If you have various clients, you can save individual templates by using the lightning bolt