Often (on SO/SE), people try to summarize the tag's meaning and Wikipedia definition in a tag wiki. This is not what a tag wiki should contain. It is rather unfortunate that "wiki" reminds people of Wikipedia, but a tag wiki serves two main purposes:
- The tag wiki excerpt serves as a short blurb to users as to what questions that tag should be used for. Not everyone notices this, but you can hover on tags anywhere and it brings up a pop-up containing the excerpt. So it's good to think of it as a tweet – be to the point and tell them what to use this tag for and what not to use it for.
- The main body should:
- go into more detail on the usage of the tag
- point them to additional tags that they could use. For example, points from the recent discussion on graphics and plotting can be included as guidelines (although in general, I'd recommend waiting a bit to see if the discussion is settled).
- List additional resources, packages (such as the big list question from earlier today)
- Have a list of frequently asked questions (not to be confused with the site's FAQ and the other faq tab on a tag page). For example, export could point to questions on how to export and how to get rid of grey edges in polygons when exporting to PDF, etc.
- Have a list of questions that highlight the best-practices or have canonical answers. These needn't necessarily be frequently asked.
The Scala tag wiki on Stack Overflow is a decent example that lists the frequently asked questions, the food-safety tag on Cooking is an example of one that educates users and provides tips on the topic and the baking tag guides them on tag usage for alternate interpretations of 'baking'.
It will probably take a while before we accumulate enough questions to know which ones are frequently asked, which one has a better answer, etc., but it needn't be done all at one. We can do it in passes.