I see most people talking about Quality Links here. My Quality Content allowed me to rank one of my sites at #1 on Yahoo, for about 3 Keywords. I did not have that many links. Just quality content. I think Google relies more heavily on links than Yahoo does.
I never tried to rank in yahoo but after reading the answers here I don't see a big difference between the techniques we apply for google and the suggestions for yahoo ranking.
I noticed that Yahoo counts all the backlinks,Google doesn't do that,but most of the traffic it's coming from Google.