People face problems – real problems they may or may not see ... problems you might help them fix. If you're not fully established yet, then you must pitch your services to people who haven't fully realized that they need you.
Trouble is, people are naturally reluctant to pay for advice. And that's easy enough to understand.
Consulting is often a service without tangible end product. Either the topic is unfamiliar territory, in which case gauging the value of consulting is tricky; or else it seems deceptively familiar, like something they could do themselves to some extent. Maybe they simply have no space for consulting in their budget; so while they'd appreciate your advice, they're not ready to pay for your time giving it to them or gaining expertise.
Right there, you have 4 points to make:
(1) Emphasize results you'd like to help a client achieve. That's a more tangible goal for them to focus on.
(2) Help them estimate the value of those hypothetical results.
(3) Explain why going solo, winging it without a consultant, can be risky. No scare tactics necessary. You can point to plenty of non-clients with problems. And you can ask your prospective client what difficulties (if any) they're facing.
(4) Connect the dots. If you add value, then the cost of hiring you should pay for itself.
Yes, it would be helpful to start out as a celebrity with an amazing track record of successful past clients. However, all that really counts is whether you can help the next person and convince them to value that help.