Using Missing Index Information to Write CREATE INDEX Statements

Use the following guidelines for ordering columns in the CREATE INDEX statements you write from the missing indexes feature component output:

*List the equality columns first (leftmost in the column list).
*List the inequality columns after the equality columns (to the right of equality columns listed).
*List the include columns in the INCLUDE clause of the CREATE INDEX statement.
*To determine an effective order for the equality columns, order them based on their selectivity; that is, list the most selective columns first.


source: http://msdn.microsoft.com/en-us/library/ms345405.aspx