It’s all about actively marketing yourself and reaching out and introducing yourself to people.
For individual book editing, it’s almost always referrals or people I’ve reached out to on social media who have said they are writing a book. Book coaching is the same.
For publishing companies, I reach out to editors who work there and ask if they ever hire freelance editors, introduce myself, and offer to help.
I reach out to companies directly on Instagram, Facebook, or through their website contact page. I have long found great clients using social media! I’ll see that they haven’t updated their blog in a long time or have a niche where I feel I’d be valuable and I reach out to them directly to discuss if they’ve thought about hiring a writer.
For websites where I find clients, I usually respond to job ads on sites like ProBlogger, WritingAxis, Flexjobs, and Craigslist.
I don’t use sites like Upwork or other content mills for making money, I just don’t prefer them.
My very first couple of clients came from reaching out to people on LinkedIn and offering my services and one from Reddit.