Here is a GENERAL RULE that worked for me in the past:

A title should identify right away what the article or document is all about.

Also:  if possible, a title should give a sense of the importance of whatever the document is about.

FOR EXAMPLE:

“A Modern Miracle: Denver International Airport”

Obviously, this article is about Denver International Airport.

That’s why there are two things wrong with this title:

1) “Denver International Airport,” should come first, before the colon, since that’s what the article is really all about.

2) The title does not tell us why Denver International Airport is a “modern miracle.”

MUCH BETTER: “Denver International Airport: the Only Airport in the World Built with the Miraculous XYZ Technology”

Now not only do we know what the text is all about (Denver International Airport), but  also why it is important to read about it (because it is “the Only Airport in the World Built with the Miraculous XYZ Technology”).

EXERCISE:

Rewrite and improve the following title:

“Mission Impossible: Apollo 13” (Google “Apollo 13” to find out what happened to it and the reasons why it could be characterized as “mission impossible.”)

Also see: Technical Writing 101 Online Course