The primary keys to successful mobile content are brevity and focus. As one wag has said, “it’s like writing for the web, only more so.”
The mobile reader/user is not sitting in the comfort of their home or office with the screen in front of them as their main focus. Their attention is often divided, and if you expect to get through the clutter of their surroundings, you must be prepared to edit ruthlessly, trimming away as much unnecessary verbiage as possible while focusing on the clarity of your core message.
A mobile web page has to get to the point quickly, and be easy to scan and understand. “Simple” is the watchword for screens that can be as small as 120 pixels wide. The maximum size of a mobile web page should probably be in the range of 300 to 500 words, although skewing to the upper end of that range is preferable to cutting content into pieces that force the user to download more pages over possibly sketchy networks.
If starting with content from an existing desktop-based website, be sure to treat the original source as just a starting point. Think in terms of robust summaries rather than long expository text. Mobile content need to be more actionable (more hard information, less anecdotes) and focused on user needs (scanable, concise, clear, and fast loading). This is one of those situations when less can really be more.
Bottom Line: When writing for mobile, invest enough time to write less.
(Written by me, but originally published on my former employer’s site)