Currently supported categories
Category for grouping the artist(s) of an image, for example artist:caroo.
Category for grouping the characters portrayed in an image, for example character:chun-li.
Category for grouping series, for example series:dragon_ball_z.
Category for grouping Tickling tags. This category will allow to group the several tickling tags that have been used before by convention. That convention was making several tags like "armpits" ambiguous (Does the image portray armpits or tickling armpits?). This category will make the meaning more explicit, in this case tk:armpits.
We are trying to keep things simple for now. More categories might be added later after discussions with the community.
Warning 1: If you change an image's tag "chun-li" to "character:chun-li" and try to search for "chun-li", then that image will not be found. You actually need to search for "character:chun-li". This might change in the future but keep it in mind for now. Note that if you type "character:" in the main search box and wait, the auto-complete feature will show you all "character:" tags.
Warning 2: Don't go crazy with editing old tags and trying to replace them with categories. Admins can easily mass edit tags. It might be better to just make a list and publish it, for example write "dragon_ball_z -> series:dragon_ball_z" etc.
Right now we have changed the majority of the *tickl* tags with equivalent tags under the tk category. Tags like tickle_sounds are now tk:sounds. Tags like tickled_by_hair are now tk:by_hair. In the same logic, the tag tickle_hands is now tk:by_hands, while all the different "you gonna get tickled" tags are now all tk:anticipation.
All the older convention tags (like using the tag feet to indicate tickling on the feet) are left as they were. Those will be changed carefully over time.
When you upload new images, you can start using the above categories to make tagging easier.