I find it difficult to get ranked on both yahoo and google - I seem to find Google easier for some reason but I would like to know if people bother to specifically target yahoo or concentrate on Google
As far as ranking on Yahoo, I wouldn't worry too much about it. I would do all of the same things you should always do for SEO, and let traffic come from the search engines naturally. Build backlinks, have good onsite SEO, and let the search engines find you. Google gets most of the traffic, so that is where you should spend most of your time. Yahoo tends to rank different websites in the search engines, so I would post content on sites where you haven't posted content in the past, and see what happens.
you should good content that attract the peoples then you got good traffic and collect good PR links for your sites
you have to submit your blog or site to the Yahoo! Directory Submit be sure that you have the good meta tag and key words