It sounds counterintuitive, but, share everything you know on the internet for free (Blog for SEO), and then collect emails at the bottom of each post promising further valuable information.
You’ve now got a list of leads who think of you as an expert and specifically need help with your niche area. You need to email them regularly with further valuable information to keep them engaged. Occasionally sell your services to this list, while keeping it mostly informative so people don’t unsubscribe. This will become the “inbound” portion of your sales funnel.
Next, you need to create the “outbound” portion. Using your email list, send out a survey and find out what type of people are looking for consultants in your specific niche.
Once you have a good target profile, troll LinkedIn and create a contact list that fits the profile, and systematically reach out to each of them. You also should share some of your content posts that you think would be relevant to them (and that have proven to be popular) to both establish trust, and also potentially get them on the email list (not everybody needs help right now but will later).
Once you have an inbound and outbound process that’s working and you can calculate what percentage of leads eventually convert, scale it up. Hire virtual assistants to automate and dabble with ads.
Now you have more work than you can handle and have the beginnings of an agency where you can sell other people’s time for even more profit.