The MSN search engine has very similar requirements to the google seach engine. They are:-
Use only well-formed HTML code in your pages.
Make sure that all tags are closed
Make sure all links open the correct web page.
Do not have broken links.
If you move a page, set up the page's original URL to direct people to the new page.
Make sure MSNBot is allowed to crawl your site.
Use a robots.txt file or meta tags to control how MSNBot and other web crawlers index your site.
Keep your URLs simple and static.
In the visible page text, include words users might choose as search query terms to find the information on your site.
Limit all pages to a reasonable size. We recommend one topic per page. An HTML page with no pictures should be under 150 KB.
Make sure that each page is accessible by at least one static text link.
Don't put the text that you want indexed inside images.
Add a site map.
Keep your site hierarchy fairly flat. Each page should only be from one to three clicks away from the home page.