meta-tags isn't the same as meta-keywords.
Meta-tags are description, keywords, title, and all the funky additional meta information that yoast will churn out for twitter, fb and social sites.
Meta-keywords aren't really relevant, but it doesn't mean that you can't add those.
Most importantly, you should set your meta-description and title to the right one. If possible, just use yoast and it should take care the rest of the process for you - you just need to set those up and fire and forget.