Good work @Steemcleaners :) So the main rule is to use relevant tags on original high quality content. Five tags is a fine number. Not many and not to few.
Maybe we could all get more benefit from smart use of the tags. The great thing about tagging is that it is such a simple way to integrate that post in a subject related list of many good posts. Its a fast practical way to organize information. A good post usually ranges between several subjects and as you mentioned general categories like "life" or "steemit" will usually be relevant one way or another. So that will be a judgement call. With good tagging we then make it easier to find interesting posts in many different categories. A dream for the future could be for all topics to have our own special "toplist" substeems. In those toplist substeems we could find the most interesting and highly rewarded articles about the given subject posted on Steemit. It could work almost like a google search except we collect incredible quality articles from Steemit of the kind which are a joy to read again and again. With the tags it will be easier to find them :)
So all of this seems to depend on keeping a high standard in the posts. And then using relevant tags with common sense as a part of the stategy. High quality content + relevant tagging is a winner for everyone :)