Yahoo! remains a major portal, its still considered as one of the popular search engines.
Optimising for Yahoo respond the standard Content SEO guidelines, basicly keyword URL's, with some signficant additional developments for those primarily used to optimising for Google.
The major factor is that on the Yahoo! help page it strongly suggests that meta-tags will play a specific role for ranking purposes:
Yahoo! Search ranks results according to their relevance to a particular query by analyzing the web page text, title and description accuracy as well as its source, associated links, and other unique document characteristics. How Description Tags are Optimised
That means that as well as ensuring proper use of titles, h tags, and body copy, you should ensure you use proper cross referencing of meta-tag keywords with these vary page elements.
The first rule of description tags is to ensure that it reads well - Inktomi is traditionally pretty good at recognising the difference between good grammar usage for humans, and blatant keyword stuffing for spiders. Keep this well in mind.
Also, you should ensure that you make sure that not only does the description reflect the intent of the page, but you should also ensure you use keywords on the page copy. Don't try stuffing in related keywords - if it's not on the page, there's no real benefit.
Also, try to repeat some element - in whole or part - of your title and tags. This helps make your page even more relevant for the search term(s) you are specifically targeting.
OFF PAGE ELEMENTS
Anchor text
Yahoo! is placing particular emphasis on anchor text and IBL's (In Bound Links). However, unlike Google, Yahoo! seems less discriminating than Google against anchor text use on the pages that Yahoo-Slurp/Inktomi crawls.
However, do be warned that Inktomi has a reputation for sniffing out doorway pages, with some of the most respectable autogenerated content filters in the industry. So don't put too much faith in this tactic bringing significant results.
Dynamic links
Inktomi has a reputation for not being keen on dynamic pages, and it seems apparent - for now at least - that Yahoo! shares similar tastes. Therefore use static pages for your key links where you can. If that's too difficult then at least consider using a sitemap of some kind - even just a "quick links" section - to help direct spiders from static pages to key dynamic pages, as some will likely be indexed.
Of course, if you feel confident implementing it, then you can always implement a Mod_Rewrite solution. However, this isn't for the faint of heart and you should be very careful to ensure that either yourself - or whoever is implementing it for you - knows exactly what they are doing. Do note that this is not an entirely server side solution, as the software generating the dynamic pages will almost certainly require some modification of the code.
If you can't do that then all is not lost: although Inktomi itself isn't keen on spidering dynamic pages, Yahoo! does have other technology it can implement that has no issues with dynamic pages. AllTheWeb is a good example of search engine technology that doesn't discriminate against dynamic pages, is close under Yahoo!'s belt, and that could be implemented at any moment (presuming it isn't already).
Meta Search on Yahoo!
To see how much of your sites is being indexed by Yahoo! here are some useful links:
site:domain.com
Just like allinurl:/site: on Google, it returns the number of indexed documents for a particular domain. However, note that any listed documents tend to be the pages with the highest number of IBL's. (NOTE: Yahoo! does not care about http:// or www - just the domain name.)
link:URL
As with the Google link:, excepting that there is no PR restriction on the returned results.
url :URL
Find a specific document on your site, to see whether it has been indexed.
For more information on different meta-search options and uses for the Yahoo! search engine, including search of maps, visit Yahoo! help: Search shortcuts and perferences |  |
