As the mod I'm the only one who can add a new tag, but as long as the tag is existing you're more than welcome to tag your own fic.

Some people tag their own, some people don't, it's really up to you. I always go through and check every entry all the same just to make sure everything is cool.

Every author that posts to hp_misfitfics has their own archive in the memories (http://www.livejournal.com/tools/memories.bml?user=hp_misfitfics) section. I go through and archive the memories every time something is posted so all your work that is posted here can be found easily.