My main advice would be don't make your entire site in Flash - embed it into an HTML page and be sure to keep the navigation items as HTML text links. The best way of embedding Flash from an
SEO point of view is using a technique called SWFobject (http://blog.deconcept.com/swfobject/) - this loads the flash using javascript, and allows you to replicate the content of the flash in HTML so that search engines can properly index it and follow the links.
If you really want a flash-only site use SWFAddress (http://www.asual.com/swfaddress/) which allows you to have separate URLs for each section.
You may have read that Google and Yahoo have recently started getting better at reading flash - while this is true search engines still have a lot of problems with flash and HTML is always better.
Finally, even if you don't do any of this you site can still rank well if its good enough to get lots of links from high quality, relevant sites!