The current convention appears to be:
- Author names are as you would find them on the cover of a book (i.e. generally first-last, but sometimes with middle initials/names, like orson-scott-card, or only initials, like c-s-lewis). Since the tag search searches anywhere in the tag either should work fine (i.e. if you type "hein", you'll find robert-a-heinlein.
Propositions are mixed at the moment:
In general, shorter tags are better, especially since they are used in space-sensitive locations (page title, tweets) now. However, if they are too short (e.g. "way" or "prisoner") then it's unclear that they are referring to a particular series.
If the guideline was that titles four words and over drop the preposition, then only golden-compass and the-player-of-games don't match.