http://danbooru.donmai.us/uploads/new
There is written that there is an upload guide. But since some people are just tagging bad and/or are only adding tagme, I thought it would be good to also include the howto:tag wiki somewhere into the page I linked above.
Simply because it is frustrating to do tag gardening because of this, like removing tagme, and Danbooru isn't really beginner friendly when it comes to learn tagging or tagging at all.
So it should be better to directly lead users who want to upload a direct link to howto:tag right when they are new registered, something like a beginner guide or to the upload page.