i think that  the Directory submission is really important to get ranked in yahoo. you should try this and i hope you will see the difference as soon as.
I rank #1 for a keyword google sends 1900 clicks per month, very little clicks sadly, so i wouldnt bother unless there is a high search term keyword.
The easiest way to go would be to add some new content. Have you considered using content curation for example? It’s a very efficient method of creating content. It’s fast because you use content created by other people and only improve it a bit by including your own comments and ideas. It works really great because you not only have a lot of quality content quickly, but also gain trust and recognition among visitors who are more likely to return to your site and link to it. The concept of curation is explained in detail in this blog post: rubymediacorporation.com/blog/why-content-curation-should-be-a-vital-part-of-your-marketing-strategy/
Fresh and quality content is most important for getting higher ranking in Yahoo. You have to update your content on a regular basis. Then you can promote your site.
You must submit your website in Yahoo directories, join Yahoo answers, update content in your website and also apply all other Search Engine Optimization techniques..
You can improve your yahoo rankings easy than the others only you must post the new and fresh content and must get more back links to your site and must have the more traffic to your site.