Writing Excuses Episode 4: Beginnings
http://www.writingexcuses.com/2008/03/02/writing-excuses-episode-4-beginnings/
starring Brandon Sanderson, Howard Tayler, and Dan Wells
( Ze bits and pieces . . . )
The short form: don't try to write your first line first. Do make sure that your first line makes a promise that the rest of your book fulfills. Get to character and conflict fast.