best caching strategies for high traffic apis

Hey everyone, I'm trying to make a bunch of APIs faster because they get hit with so much read traffic. We're looking into different ways to cache stuff to take some pressure off the database and speed up responses. What do you guys usually do to set up caching when you've got a lot of traffic? Are you mostly using in-memory caches like Redis or Memcached, or have you found something else works better? Also, any ideas on how to handle cache invalidation for data that changes a lot would be really great.