This policy has wide acceptance among editors and is considered a standard that all users should follow.
Feel free to propose any changes to this policy, but please make sure that changes you make follow the official process and reflect consensus on the discussion page before you put them into practice. Any big changes need to be Adopted or Decreed to be enforced as policy.
Quests should be named with the "Quest:" prefix, followed by the exact name of the quest. If a quest line has the same name for multiple quests, the first quest by that name should follow the previous convention and further quests in the line should be disambiguated with parenthetical text signifying the quest part, i.e. (2), (3). If there are two quests by the same name, but they are different for Horde and Alliance you can:
Make an article explaining both sides of the quest.
Make two articles, one with the exact name of the quest and a second disambiguated with either (Horde) or (Alliance).
These rules ensure that anyone typing in Quest:Quest Name will be able to find the quest they want. The original icon should have a disambiguation link at the top pointing to the second article. For example, Chen's Empty Keg, Chen's Empty Keg (2).
Some quests use punctuation that simply will not work in the Wiki. There is no policy on the matter, but it seems that often the best thing to do is to just skip those characters. See the policy talk page for more information.
Character pages should be listed under the character's full name (first and surname) if known, excluding titles such as "King" or "the Destroyer". For example, Arthas Menethil, Terenas Menethil II, Blackhand.
It should be noted that some races and characters do not have "surnames", names like "Hellscream" or "Lightbringer" (or "The Lightbringer") are in fact titles, these are allowed as the names are how they are commonly known or can disambig between more than one version of the character, for example Kazzak the Supreme.
For minor characters (normally NPCs) whose full name is unknown, names should be listed under the name that is displayed in-game, including case, e.g. High Executor Darthalia.
API function descriptions are prefixed with "API " and then exactly as the function name, with the same capitalization and no whitespace. For example, API GetShapeshiftFormCooldown. Object methods use spaces rather than colons, e.g. API Font GetFont. See API Notation and Conventions for details.
Player character articles should be located as subpages of the server on which the player resides, or (though less preferred) located as subpages of the author's user page.
All other articles should have the first word capitalized (this is unavoidable) and any additional words in lowercase. The exception is that proper nouns are always capitalized. For example, Help:Starting a new page.
Articles should also not include definite or indefinite articles ("the" and "a/an") at the beginning of the page name. For example, use First War to refer to the event, not The First War. There is an important exception to this rule: "the", "a" or "an" is included when it would be capitalized if it appeared in text. This exception applies to quest articles, titles of books, games, and similar works.
Articles that are lists, e.g. Paladin spells. This may cause extra work in attempting to say "foo is a [[paladin spells|paladin spell]]", but the suggestion is to set up "paladin spell" as a redirect to "paladin spells" if there is no page describing the general properties of what a "paladin spell" is.
In cases where you feel that visitors are likely to type in a plural name directly in the URL, it is perfectly acceptable to create a redirect, e.g. Dragons → Dragon.
For "simple" items, it is also perfectly acceptable to create a lower-case redirect, e.g. linen cloth → Linen Cloth. Note that the case of the first letter is ignored in the wiki software: dragon is the same as Dragon, no redirect necessary.
Redirects of category pages are never allowed according to the category policy.
As for code in linking to each of these, you can type
[[Onyxia (tactics)|]]
and arrive at these two links: Onyxia. The parser will appropriately cosmetically drop what is found in parentheses.
Subpages and namespaces
For the purpose of capitalization, after the colon for a namespace is considered the start of the article title. For example, WoWWiki:Policy. Additionally each subpage is considered the start of an article name.
Race names ("humans", "dwarves", etc.) are written in lowercase in WoWWiki. This also goes for when they appear in page names. Note that "nationalities" are capitalized, i.e. "Forsaken".
Obviously, the MediaWiki software will always capitalize the first word in the page title, and there is nothing we can do about that. This rule is only relevant for when a race is mentioned later in a page title.
Note that regardless of this rule, articles named according to in-game NPCs are still capitalized as they are in-game, as per the NPC articles rule, above.