Not only is InVision's newsletter a great mix of content, but I also love the nice balance between images and text, making it really easy to read and mobile-friendly -- which is especially important, because its newsletters are so long. (Below is just an excerpt, but you can read through the full email here.) We like the clever copy on the call-to-action (CTA) buttons, too.
If links and looks are set, begin interacting with the page. Abandon it, adjust the window size, convert. Are error messages appearing when they’re supposed to (if, for example, you don’t input all the form’s required info)? Is your CTA button working? If you abandon the page, are you retargeted with ads? When you resize the window, does your landing page respond accordingly?