As far as I know, Yahoo! focuses more on the age of the website. Thus, after registering your domain, you may want to let it age for more than a year before building relevant backlinks from high quality pages in a similar niche. I've also read that you must purchase the same website name with and without dashes. Like Yahoo!, Bing also looks at the age of the domain as a major element. The older is your website, the higher the ranking. Moreover, make an effort to obtain links from pages using your keywords in the title tag.