We've all seen plenty of brochures (and websites) that fail to accomplish their purposes.
Here's a pretty good article with tips on good brochure design.
I think the creative process for every brochure (or website, etc.) needs to start with a purpose statement for that promotional asset. Too many organizations waste money on creative projects that are designed to please "the boss" rather than accomplish their purpose in the marketplace. And it's almost always best for the purpose to be narrow and focused rather than broad and scattered.
Really good creative requires strategery - a well thought out strategy combined with effective imagery. And strategy begins with understanding purpose... what are we trying to accomplish here anyway? Then every element of that creative asset needs to be molded around its purpose, or eliminated.
Purpose provides a critical touch point in the creative process.
I'm amazed I see it used so infrequently.