With the increase in mobile browsing & search, mobile websites should be built properly to drive more traffic from search & provide better customer experience. Some of the check list from Google webmaster central to improve mobile websites are
1) Optimize crawling, Indexing & search experience. Unblock resources that are robots.txt disallowed. Implement search engine best practices.
2) Optimize mobile persona workflows for your site.
3) Seperate mobile site & include CSS @media query.
4) Search integration with mobile apps. Build for mobile behaviour & also provide for social sharing.
5) Remove cumbersome extra windows from all mobile user-agents. Also remove features that require plugins or videos which may not be found in the users device.
6) High traffic, poor user experience mobile pages should be designed properly.
7) Tablet users be served with the desktop version or if available, the tablet version.