Internal linking of your site should be good for yahoo try to add complate page URL in you site and avoide writing click here or link of image try to add as much as text link and connect the pages internally so you will get good raking on yahoo too . . . .
Well Yahoo is into metatags and huge amount of backlinks for a perticular keyword.I think keyword stuffing can work for Yahoo.
First you have to understand that Yahoo is not popular than Google .. because mostly peoples prefer Searching on Google that;s why we cant get lots of visitors & 1 more thing Either your Website is not in top 10 Search result of yahoo.. That;s why Or Dur to average volume of keywords ...