meta tags play major role for your site,you prepare tags based on your website that is what purpose your site is for and you take related searching keywords,for which keywords visitors are more,these things you may find from keyword suggetion tools.
It isn't absolutely necessary to include meta tags for seo purposes. sites can rank well enough without them, and often do. In fact, due to abuse and over-use over the years, meta tags began to be ignored by search engines, or simply not counted toward scoring pages.
Though major search engines do not provide much importance to Meta tags, but still its better to optimize Meta tags. Basically of all the Meta tags the two primary tags that play a role in optimization are the Meta Keywords tag and the Meta description tag.