Here are two great useful posts on my site about mobile website.
The first is about creating responsive layout and the second one is resolutions for the media queries and screen sizes. These two posts are all you need.
First, you have to know that the Web site design and construction generally used for computer browsers is not compatible with that of mobile devices. For your site to work well on a mobile handset, it must follow the accessibility design guidelines for building mobile Websites which are set by the W3C.