Any special about keyword research in Yahoo? Check out the autocomplete feature in Rank Tracker SEO tool, and use keyword planner to find your best-performing keywords in Yahoo!
In case your target market is Russian-speaking countries, you have to be a pro in Yandex SEO. Though very similar to other search engines, Yandex has its own peculiarities. We compiled a guide with all the things peculiar to Yandex as well as advice on how to optimize for them.