I have site still it is not well ranked in yahoo india but it is doing well in US yahoo http://www.onlinejobshelp.com
I tried using more yahoo sites like yahoo answers, groups and more and then I always make sure that I have good and relevant contents.
yahoo search traffic is nearly non-existant. Most people use yahoo for finance and email and stuff like that.
I would suggest to continue building strong relevant back links, a great way to do so is by making sure when you create a link that it is a "NoDoFollow Link". Mozilla Firefox offers a great ad on tool for it because if you are not using it then you may have many back links that are in fact dead links.
Have a look at your keyword first and research it.. use submission technique.yahoo answer help yahoo greatly.
yes getting traffic from yahoo is difficult.. i hardly get a few visitors from yahoo. I guess this article will help you to get some idea on getting traffic from yahoo... Improve yahoo rankings
Yahoo is slower and they get picky and somewhat take more time to choose the "right" sites to rank. They like actual depth and well developed sites. Backlinks, submissions and such help a lot. It's harder to rank in Yahoo than Google.