A must-bookmark guide to content audits by Lauren Pope:
Content audits aren’t one-and-done projects. Content degrades over time. Sites grow. Strategies evolve. User needs change. If you don’t build in a way of keeping on top of it, you’ll find yourself back where you started in a year or two – sitting on a pile of content nobody is quite sure about.
This is such a useful post, whether you're experienced with content audits or attempting one for the first time.