I don't think that there is any difference between any ethical tactics. Rather yahoo uses a different way to calculate the SERP's, it is always ahead in counting the backlinks. But due to search volumes, Google is preferred over Yahoo and also a complex one to be understood.
See, both have separate engines so, obviously the algorithm is different. You need to concentrate on some on-page optimization techniques also that will help you increase your rankings on yahoo simultaneously working for getting more and more back links.
basically Both have different algorithms and they move in that directions.
there are a lot of differences between SEO Google and Yahoo.
Yahoo explorer fetches top high authority pages but Google picks them according to site map.
Yahoo indexes those pages who are very worthy, content enrich, high traffic but Google concentrates on back links and content.
I hope, may be something wrong with your on page optimization. Am sure with this once you following Google algorithm and work on it surely you will get improvement in yahoo search engine. Because yahoo search algorithm, most of the factors are similar to Google. So very competitive to get SERP in Google only not yahoo you will get good position in yahoo easily.
There is no such a different for the Yahoo and Google . They follow the traditional methods for site optimization . They have mirrior differnce Google gives more focus on the quality and there is difficult to optimize the site and on the Yahoo it is realitivily easy to optimize the site .
Google SEO is the both On-page and Off-page SEO strategies. But yahoo optimization is about only On-page SEO technique. This is the only difference between Google SEO and Yahoo SEO. So its easy to get indexed in yahoo.
there might be some problem in your on and off page optimization so that why your ranking is affected. There no big defference between both search engine its just following the search engine guidline..
well i think there is no google seo or yahoo seo..
there is one seo and other sem..
just follow the regualr seo tricks,build backlinks,improve alexa rank..
this is all you have to do..no worries about yahoo and other search engine