when should you cache database query results?

hey everyone, i've been thinking a lot about performance lately. we have a few read-heavy endpoints that really hit the database hard. obviously, caching is the usual answer, but i'm trying to figure out the exact details. what are your general rules for deciding when to add a cache for database query results? do you look at how often a query runs, how often the data changes, or something else? i'm really curious to hear your strategies and any problems you've run into.