The distinction between freelancer and consultant is irrelevant. What is relevant is what consulting is.
Consulting typically means solving problems for clients. Often that starts by assessing the client's environment to gain insight into the client's stated problem, then defining an appropriate solution which the consultant may or may not lead/drive or be involved in implementing.
That of course comes with a lot of additional skills such as strategy, managing stakeholders, risks and so on.
Best book I can recommend is "Designing Solutions for you Business Problems" by Betty Vandenbosch. Because great consulting is not just about efficient problem solving. It's just as much creative problem finding and building relationships to make a solution happen.
As for finding customer 1 - I did it by demonstrating the inefficiencies of the software development practices at a civil service I was contracted (freelance, I guess) by. That was 14 years ago. After that it's been word of mouth.