Not only should keywords be relevant, get decent traffic and not have a ton of competition but they also need to have commercial intent. This means that the keyword looks like a keyword someone would use when searching to buy something. For example the keyword "SEO" might be searched mostly by people who are learning about seo. The keyword "SEO consultant" or "SEO services" looks more like the type of keyword that someone looking to hire an SEO provider would use - this is what is meant by commercial intent and your SEO consultant needs to be aware of this.