when should you implement data caching strategies

Hey folks, I've been thinking a lot about performance lately, especially with our read-heavy services. We're seeing some significant load on the database, and I'm considering implementing caching. But there are so many strategies out there - simple in-memory, distributed caches like Redis or Memcached, even edge caching. When do you all decide it's time to pull the trigger on caching, and what factors influence your choice of strategy? Curious to hear your war stories and best practices.