What's a good caching strategy for stuff that's accessed a lot but doesn't change much

hey folks, i'm dealing with a pretty standard issue and was hoping to get some ideas. we've got user profile info that gets looked at a lot, but not changed much. currently, we hit the database for every single request, and it's starting to slow things down. i was thinking about putting a cache in front of it, maybe using Redis or Memcached. what's your usual approach for dealing with cache invalidation when the data *does* get updated? how do you find that sweet spot between keeping the cache current and actually getting that performance boost