
First up all, Bing shouldn't even compete against Google. Microsoft should be targeting marketshare of Yahoo, AOL, and Ask.com. At the same time, keep an eye on Google's move.
Eat your own dog food: Microsoft must integrate much better Bing search to all of its properties and Research tools. I see that happening already. Integrating Microsoft Live products, Mobile tools to Bing.com will make more popular.
Commitment: Microsoft must show the commitment to Bing Engine regularly, everytime news comes about Bing, people go and try the site, then after a while they go back to Google. Microsoft should make news regularly to add new features, tutorials on how to do better search, and post blogs. Part of your frequent news, make some deals along the way with big companies to make Bing.com the home page to show the commitment to the website. Just like Google, Microsoft must come up with one place for Bing.com search engine updates communication blog. release the funny videos of Bing Decision engine to Youtube or any other video sites.
Bing for Geeks:When I need to search for errors in any software, I don't go to their website and look for solution, I Google it. Microsoft should attract all techies and give them the best results than Google. Better Indexing the help files, user guide and administration guide will make the Bing as techies home page. This in turn brings the families of techies to Bing.com site.
Bing News: Not even close to compare to Google. Add more data source to news, and continue to add more upgrades to Bing news
Expand Internationally: Success of the site depends upon how people outside US use it to influence the US marketshare. Microsoft should use all its international site to advertise Bing.com and bring more international visitors. Microsoft Spaces social networking tool is not as famous as Facebook or Orkut. Microsoft must reinvent the Spaces or integrate much better to bring results from sites like Twitter, Facebook, Myspaces ...
Household name: Even my daughter says just Google it. How do you make it household name ? it comes back to building the brand value. you convince the young generation to use it, then Bing succeeds.
Bing API: Build web applications around Bing. Microsoft is master in providing APIs to integrate websites to Bing search results. I see Google one step ahead of API and tools, currently Google Analysis, Gmail, Google Maps and other tools are widely popular.
Innovate: add more innovative features where other search engines are missing Like Videos and Images done in Bing.com. Always consider the users. if they think it is annoying, then don't add it.
Keep advertisers happy: If your sponsors are happy, that is, give them the tools and features they need to simplify the signup process. Google provides Analyzer and other tools to lock in the users to stick to Google properties. In exchange, Google indexes users site.