With the coming of Google, the traffic in a number of search engines has been affected, MSN being one of them. But it has reinvented itself in a number of ways leading to a new and better search engine. It is strongly advisable to webmasters to optimize their sites for MSN as well.
Content is the single largest factor that influences rankings on MSN. Content is the king here. With content come the keywords. These are part of the content and are equally important. Choose the correct keywords and place them in a way that the keyword density is adequate. As far as the written copy is concerned the density of the keywords should be much more than for Google. In fact, the keyword density for MSN should be thrice than that for Google. Other than the written copy the keywords should also be place don the page titles, headings and URLs.
Another tried and tested tactic is to include the keyword or the keyword phrase in the page title tags. All the major search engines encourage this practice. However, this does not mean that only keywords should be strung together in a tag, if this happens the search engine will leave the site out as spam.
Unlike Google, MSN lays huge weight on Meta tags. To use this feature to the fullest possible potential, one should have unique meta tags for each page of the website. Apart from this an accurate site description is also essential. The meta tags for the pages should reflect on the content in the pages. They should not merely be keywords and keyword phrases.
Internal site links play a huge role in MSN optimization. Internally, the site should be extensively linked and the contents of the receiving page should be similar or in relevance to the content on the anchor page. Again, this is another way I which Google is different from MSN as it does not give too much importance to internal site linking. But again these two search giants equally value the external links coming into the page. Along with the number of external links coming in, their quality is also important. It is better if the links re from sites with relevant or thematically similar content.