The following is a sample of 18 best practices extracted from the 60 available in the Last Call version of the Mobile Web Best Practices.
Ensure that links provide a thematically coherent experience when accessed from a device other than the one on which they were captured.
Exploit device capabilities. Do not take a least common denominator approach.
Provide minimal navigation at the top of the page.
Assign access keys to links in navigational menus and frequently accessed functionality.
Do not create periodically auto-refreshing pages, unless you have informed the user and provided a means of stopping it.
Ensure that content is suitable for use in a mobile context.
Divide pages into usable but limited size portions.
Limit scrolling to one direction, unless secondary scrolling cannot be avoided.
Ensure that material that is central to the meaning of the page precedes material that is not.
Do not use images that cannot be rendered by the device. Avoid large or high resolution images except where critical information would otherwise be lost.
Do not use frames.
Resize images at the server.
Create documents that validate to published formal grammars.
Use style sheets to control layout and presentation, unless the device is known not to support them.
Provide informative error messages, and a means of navigating away from an error message back to useful information.
Attach caching information to the content.
Keep the number of keystrokes to a minimum.
Provide pre-selected default values where possible.
See the full list of guidelines at http://www.w3.org/TR/2006/mobile-bp/.