The pre-written parts should serve as a template around which you build the rest of your cover letter. (blog.gojobhero.com)
Ensure that your name is bolded and in a larger font than the rest of cover letter. (resumebuilder.org)
Try something that will hold any reader's interest, but be careful — too interesting and you run the risk of it not transitioning well into the rest of your cover letter. (thejobnetwork.com)