1. Congrats on building a successful business.

2. It is important to look at your existing business and see what other services you can offer to the existing client base before you try to pivot the business.

3. What services do your customers use other firms for that you could bring in-house without increasing your overall expenses?

4. Examples:
a. Translating the writing into other languages.
b. SEO writing
c. Developing Brand Voice / Brand Guidelines
d. Ghostwriting

5. I would check out www.contently.com and some of their competitors who run successful marketplaces for writers and companies.