Meta tags is an old topic discussed and argued about in hundreds and hundreds of blog posts. We all know that good Meta Title and Meta description can improve click-through rate from the SERPs and help rankings.
Writing Meta tags for Yandex, however, is a bit special. What you need to know is that Yandex only displays your Meta title and not Meta description! Instead of Meta description is pulls a random piece of texts from the ranking page. How Yandex chooses the snippet is a mystery.
Some Russian SEOs speculate that it is usually a piece of text on the page with the highest keyword density that ends up being your Yandex Meta description. I would argue with that. I have seen many times how completely irrelevant words appeared in the snippets (e.g. copyright or year from the footer etc.). Besides, the snippet changes every 1-2 weeks.
Once I met a Yandex representative at some SEO conference, and he told me that Yandex has employees, who manually go through websites and select snippets. He also mentioned that Meta description is too easy to manipulate, and it can mislead their users… Well… =) I wouldn’t trust that one :-D
I also noticed that the quality of snippets vary among segments. That is, if you are in finance or law, your snippet is more likely to make sense than if you are in gambling (yeah.. no search engine likes spam).
The conclusions from all this:
1. Write catchy Meta titles. People will see them and react.
2. Yandex does not display Meta description. Try to display the best information in the title.
3. Make sure all texts on your pages are proper. Write good grammatically correct and selling copy! Remember that any random snippet can end up in SERPs!