I believe that yahoo might have another algorithm then google does. Maybe it worth to learn first and then act?
Here are some things you can do: -build up many more backlinks...Yahoo likes websites with a large number of backlinks -improve your internal link structure as Yahoo counts internal links as backlinks -if possible keep adding more content to your website to increase your internal link count -submit a sitemap to Yahoo to ensure there are no indexing problems Mostly it will come down to backlinks though. Something like your DP forum signature link is an easy additional 100+ backlinks.
It's thought that Yahoo is more of a language based search engine, and content is more of an important factor (than google considers it to be). Lots of keyword optimised content, keyword stemming and variations of keywords are believed to be important. Inbound links are of course very important to Yahoo too so more links is never a bad thing. There's a good article on webpronews about this - and another on evolt.org about how to satisfy "The Big Three".
Getting more backlinks helps tremendously! Plus, having the Keyword in the url will make it happen for you.