As of now, tag group pages on wiki look differently:

• some include table of contents (like tag group:body parts), most do not (like tag group:hair)
• some mark tags differently based on their use count (like tag group:wings), others do not apply special formatting (like tag group:face tags)
• some capitalize tag names they list (like tag group:shoulders), others list tags in lower case (like tag group:eyes tags)

additionally: rarely shorthands for a tag is mentioned (like in tag group:hair styles), rarely short description of a tag is included (like in tag group:neck and neckwear).

My objective is to unify the appearance of tag groups, but for this we need a written set of rules of how tag groups should look like.
Here are some questions to begin with:

• should tag group include table of contents?
• should tag group distinguish tags by formatting?
• should tag names be capitalized?
• should tag shorthands be mentioned?
• should tag descriptions/clarifications be included?

yellow_apple said:

• should tag group include table of contents?

That really depends on the size of the group. For sprawling lists with numerous sections like tag_group:attire or tag_group:food_tags, a table of contents could come in handy. For smaller pages like tag_group:board_games it would just be a waste of space.

• should tag group distinguish tags by formatting?

Please, no. The number of times a tag has been used is fairly trivial information in the first place, and all the italics and underlines and curly braces everywhere make wiki pages practically unreadable. See my complaints and others at topic #15990.

• should tag names be capitalized?

Usually I only capitalize tags that are proper nouns.

• should tag shorthands be mentioned?

The slash-aliases have been obsolete since autocomplete was introduced, and there are plans to do away with them entirely. There's no point in promoting their use now.

• should tag descriptions/clarifications be included?

Only when necessary.

I worked on a number of those groups years ago so they are just outdated. But I would like some consistency if the admins have one.