HTML Design Guidelines
Web design approach should have the following layers that will be added using a progressive enhancement strategy:
2. Insert in the document any special tags or classes required for device-specific functionality, such as call-to links or a file upload form control.
3. Optionally, from the server, decide which MIME type you will be using and recognize the device.
4. Optionally, from the server, replace the special tags inserted in step 2 with real markup depending on the device capabilities.
5. Add one CSS layer for basic devices, one for high-end devices, and one for some specific smartphones (Android and iPhone devices, for example). You can insert all the markup at the same time using CSS media queries, or use a server-side mechanism to decide which CSS file to apply.
7. Add an unobtrusive Ajax layer for content updating, capturing the onclick event of every link.
9. Optionally add widget support using a new layer.
References to design guidance materials and workshops.
Compilation of many more links
Some design and wireframing tools
Mobile readiness testing tools
Plugins and Frameworks