Short but sweet tips:
When I use tags, I prefix them with the "@" symbol. It's annoying to use on iOS so I use this TextExpander snippet:
I also have one for project tags, which are prefixed with an underscore. Even though this duplicates some of the functionality of my Markdown collection it's easy to remember when I am thinking about a "tttag".
I don't delete many snippets. I archive them. I have two inactive snippet groups. One is called "Deactivated" and one is called "_Development". Just set the "Expand in" setting to "No Applications (Disable)" and uncheck the "Suggest abbreviations"