Kenneth Davila took on this subject, substituting for the scheduled speaker who was feeling a bit under the weather.
To start, you have to decide if you want to do native development or responsive design. Native development leverages device and OS specific features. Responsive design leverages current architecture.
Rich content is a key term when talking about the web. You want to have a "rich share." So a UI design is driven by the goals of the site, is influenced by the content strategy, is defined by the system architecture, and is developed in context of the target audience and device.
Your site's content acts as a road map for users. Keep language, styles consistent. Don't break the Back button.