On the "Ask Question" page, when the keyboard focus is in the entry box for "Tags", on the right hand side we see a box with some information on "How to Tag".
Can we add an item in there to indicate to users that, after selecting a tag, they can hover the mouse over the selected tags (which now appears below the entry box) to read the Tag-Wiki excerpts, to see if they have selected an appropriate tag? I think this will help with the problem of new users applying grossly inappropriate tags because they don't actually understand what a particular tag is for. (This happens a lot on Math, but also a bit on TeX and other sites that I read.)