So for different videos, I use different tags. For the long hair videos, it's a lot of "long hair for men" "long hair for guys" "guys long hair" "how to grow long hair" "how fast does hair grow" etc. It gets repetitive, but I make informational videos on that subject, so I want to cover any questions that people have (as long as the video covers that topic) in whatever way they may ask it.
For the puppet videos, I always use "puppet" "puppets" "puppetry" "puppeteer" etc., because those are fairly unique terms in YouTube, so they're easy to show up fairly high on lists. Of course, the really high-ranking puppet videos are for little kids, so I'm still not big on any really important searches, but I figure it'll catch on.