The W3C has published the candidate recommendation of Mobile Web Best Practices 1.0 Basic Guidelines. Here's the summary of the guidelines:
[THEMATIC_CONSISTENCY] Ensure that content provided by accessing a URI yields a thematically coherent experience when accessed from different devices.
[CAPABILITIES] Exploit device capabilities to provide an enhanced user experience.
[DEFICIENCIES] Take reasonable steps to work around deficient implementations.
[TESTING] Carry out testing on actual devices as well as emulators.
[URIS] Keep the URIs of site entry points short.
[NAVBAR] Provide only minimal navigation at the top of the page.
[BALANCE] Take into account the trade-off between having too many links on a page and asking the user to follow too many links to reach what they are looking for.
[NAVIGATION] Provide consistent navigation mechanisms.
[ACCESS_KEYS] Assign access keys to links in navigational menus and frequently accessed functionality.
[LINK_TARGET_ID] Clearly identify the target of each link.
[LINK_TARGET_FORMAT] Note the target file's format unless you know the device supports it.
[IMAGE_MAPS] Do not use image maps unless you know the device supports them effectively.
[POP_UPS] Do not cause pop-ups or other windows to appear and do not change the current window without informing the user.
[AUTO_REFRESH] Do not create periodically auto-refreshing pages, unless you have informed the user and provided a means of stopping it.
[REDIRECTION] Do not use markup to redirect pages automatically. Instead, configure the server to perform redirects by means of HTTP 3xx codes.
[EXTERNAL_RESOURCES] Keep the number of externally linked resources to a minimum.
[SUITABLE] Ensure that content is suitable for use in a mobile context.
[CLARITY] Use clear and simple language.
[LIMITED] Limit content to what the user has requested.
[PAGE_SIZE_USABLE] Divide pages into usable but limited size portions.
[PAGE_SIZE_LIMIT] Ensure that the overall size of page is appropriate to the memory limitations of the device.
[SCROLLING] Limit scrolling to one direction, unless secondary scrolling cannot be avoided.
[CENTRAL_MEANING] Ensure that material that is central to the meaning of the page precedes material that is not.
[GRAPHICS_FOR_SPACING] Do not use graphics for spacing.
[LARGE_GRAPHICS] 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.
[USE_OF_COLOR] Ensure that information conveyed with color is also available without color.
[COLOR_CONTRAST] Ensure that foreground and background color combinations provide sufficient contrast.
[BACKGROUND_IMAGE_READABILITY] When using background images make sure that content remains readable on the device.
[PAGE_TITLE] Provide a short but descriptive page title.
[NO_FRAMES] Do not use frames.
[STRUCTURE] Use features of the markup language to indicate logical document structure.
[TABLES_SUPPORT] Do not use tables unless the device is known to support them.
[TABLES_NESTED] Do not use nested tables.
[TABLES_LAYOUT] Do not use tables for layout.
[TABLES_ALTERNATIVES] Where possible, use an alternative to tabular presentation.
[NON-TEXT_ALTERNATIVES] Provide a text equivalent for every non-text element.
[OBJECTS_OR_SCRIPT] Do not rely on embedded objects or script.
[IMAGES_SPECIFY_SIZE] Specify the size of images in markup, if they have an intrinsic size.
[IMAGES_RESIZING] Resize images at the server, if they have an intrinsic size.
[VALID_MARKUP] Create documents that validate to published formal grammars.
[MEASURES] Do not use pixel measures and do not use absolute units in markup language attribute values and style sheet property values.
[STYLE_SHEETS_USE] Use style sheets to control layout and presentation, unless the device is known not to support them.
[STYLE_SHEETS_SUPPORT] Organize documents so that if necessary they may be read without style sheets.
[STYLE_SHEETS_SIZE] Keep style sheets small.
[MINIMIZE] Use terse, efficient markup.
[CONTENT_FORMAT_SUPPORT] Send content in a format that is known to be supported by the device.
[CONTENT_FORMAT_PREFERRED] Where possible, send content in a preferred format.
[CHARACTER_ENCODING_SUPPORT] Ensure that content is encoded using a character encoding that is known to be supported by the device.
[CHARACTER_ENCODING_USE] Indicate in the response the character encoding being used.
[ERROR_MESSAGES] Provide informative error messages and a means of navigating away from an error message back to useful information.
[COOKIES] Do not rely on cookies being available.
[CACHING] Provide caching information in HTTP responses.
[FONTS] Do not rely on support of font related styling.
[MINIMIZE_KEYSTROKES] Keep the number of keystrokes to a minimum.
[AVOID_FREE_TEXT] Avoid free text entry where possible.
[PROVIDE_DEFAULTS] Provide pre-selected default values where possible.
[DEFAULT_INPUT_MODE] Specify a default text entry mode, language and/or input format, if the device is known to support it.
[TAB_ORDER] Create a logical order through links, form controls and objects.
[CONTROL_LABELLING] Label all form controls appropriately and explicitly associate labels with form controls.
[CONTROL_POSITION] Position labels so they lay out properly in relation to the form controls they refer to.
