Use a "Keyword" meta-tag to list keywords for each page of your website. Use distinct lists of keywords that relate to each specific page on the site. Do not use one broad set of keywords for the entire site.
In Bing Webmaster Tools (lol) there is a Tool to "Check SEO" and it does give points off for having no keywords metatag. I never ran to start adding them back, but left one script option set to use it in a limited environment to see if it does better with Bing than others. Too soon to know anything.