When should we think about adding a caching layer to our APIs?

hey everyone, I'm thinking about API performance. We've got a few endpoints that are hit pretty frequently and are starting to put a strain on the database. We've talked about read replicas before, but I'm curious about adding a dedicated caching layer, like Redis or Memcached, in front of some of these. What's your experience? When did you find that introducing a cache actually solved more problems than it created? What are the common pitfalls to watch out for when implementing this?