Interesting analogy from the May edition of Computers in Libraries:
Good promotion is like Chinese food. When it's done right, it's slightly enticing and pleasantly satisfying. And shortly after it's finished, you want to go back for a little bit more. Creating good promotion can be like preparing Chinese food. You may or may not have all the right tools and skills. If not, then you probably want to order out to get it. But you'll choose your vendor carefully, to be sure that you'll get just the right flavor combination that you're looking for.