Meta Tag keywords

I am doing a website for a spa.   Their services offer many types of massages, facials, pedicures, manicures etc.  I would like to add the list of services to meta keyword tags so that if someone searches a service they offer, they will be found in their google search.  How is the best way to do this.  I read an article that meta keyword tags are out dated.  Is that so?  How do I get all  my services out there if keywords aren’t used.   Or should I use a plugin like Meta Tag Manager?  Your thoughts would really be appreciated.