Google owns 75% of all search engines. If you can rank well for Google... you will definitely rank high in yahoo also.... Don't be panic for yahoo. optimize your site for Google.... Work hard on it..... Go for white hat SEO......... You will rank high for yahoo for sure.
I just do article submission in the article sites which come on ranking for long tail keywords. I also do link exchange with site which are peforming well in yahoo. As per my experience these two things are enough to get ranking in Yahoo.
agree on this, yahoo love inpage optimization, we done it for some of our site and it get rank better
You can improve your visibility in Yahoo by submitting your link to Yahoo Directory. The inclusion, however, takes some time. You should also post messages in Yahoo Answers.