I've had most success in hiring copywriters who are eager to learn and then teaching them the fundamentals related to creating content-- keyword research, interlinking and thinking of who/how their content will either further business goals or help with generating backlinks. The technical component is easier- just look for anyone with Screamingfrog on their resume or be willing to teach someone who is semi-technical.
2. A good SEO will say there is no such thing as a good SEO, so look for humble players
3. If you’re having trouble searching - “SEO” is unlikely to be In their title. Look for “content marketing” as a skill instead
4. As a last resort, Learn some yourself and at least you’ll be able to lay the foundation.
Don't look for generalist SEO people, but instead content marketers with experience in your industry.
I've seen so many of our clients get crappy keyword research because the consultant/SEO person they work with doesn't actually know their audience well.