This is a great white paper on the latest trends in e-mail marketing that you can use to be a consultant when selling newsletter sponsorships.
The white paper is written for sophisticated marketers sending out their own newsletters, not buying sponsorships on ones like you are selling. But there are some great best practices that you can use to pursue a consultative dialog.
Use it on a sales call:
There are two best practices in particular that stand out. Show your client the study and then point them out:
"#5 Test. You might be surprised by the results"
Show them the best practice and ask if they do testing or post campaign evaluation. Great way to get your client talking about evaluation and expectations of the sponsorship you are trying to sell.
"#6 Include video links to boost click response"
Video is the hot thing to build traffic. Have they considered using the banner your are selling to link to video? Ask what else are they considering a link to? For small and mid sized accounts this is where you get to talk about how best to motivate your readers to action.