Last year, I made six-figures from consulting on the side (while I had a full-time job). Here's how I did it...
I think a lot of "wantrepreneurs" overcomplicate the process of starting a business, and just throw up their hands because it can seem overwhelming and complicated.
A lot of my work came from referrals. By simply finding one person who needed help, I was able to two additional clients who needed help (that came recommended by the first person).
The first person found me on LinkedIn, so I would look into optimizing your LinkedIn profile. Search around for consultants in your industry and see how they write their headlines and biographies especially.
If you want to scale to a large company, it first starts with one client. And snowballs from there.
One great tip I've heard is whenever you have a client, ask them "I don't spend anything on marketing because I want to spend all my time helping you. So I rely on my clients to give me more referrals. Are there 3 friends you know who would be interested in my services?"
I think you can grow a sizable consulting business through referrals only. Most people overcomplicate thinking about Facebook Ads, hiring a bunch, and other things.
Walk before you can run!