1. Screen size
A mobile device will typically have a display area of either 320x240 or 160x120.
Your mobile web page should be designed to fit within these dimensions, as larger pages (for example, a page designed for an 800x600 PC monitor) will not be displayed properly. This can make finding information difficult.
2. Input fields
As a general rule, it is more difficult to enter text or navigate around a page when using a mobile device.
Avoid the use of forms if at all possible.
Present links in an easy to use manner.
It can also be difficult to enter URLs on a mobile device, so keep it short and simple whenever possible.
3. Bandwidth
Mobile networks are not able to transfer data at the same rate as wired networks, resulting in longer load times.
The use of large graphics should be kept to a minimum.
4. User goals
Most people will access a web page from their mobile device with the intention of finding specific information or content.
Try to make this as easy as possible for the user.
Long menus, or multiple "steps-to-content" should be avoided if possible.
5. Limitations
Most web browsing software on mobile devices are not up-gradable, and lacks some functionality present in PC-based web browsers.
Avoid using scripting, style sheets, re-loading pages, and other plug-ins whenever possible.
Using unsupported functionality can cause page errors, crashes, and an overall unsatisfactory experience for the viewer.