How to design site for mobile browsing

We are having our site designed at the moment. Please could someone point me in the right direction - what makes a website successful when browsed on a mobile?

Thanks

Mainly the right resolution, and probably server executed functionality would be better.

Oh... and if I may add my two cents worth - you have to find the fine line between size and functionality. Mobiles use the four directional keypad (normally) so don't put too many links and have to scroll down for ages. At the same time, some people are paying per megabyte or have slow connections so it should be quick and precisely what they need. I find that most of these websites choose quick links or most used links at first and then content... then they can find their way quickly.