If you're a self-identified say, "Ruby freelancer", the value proposition is "I am an independent Ruby developer for hire". For staff augmentation gigs or applying for a FT position, this is all well and good, because whoever's hiring is looking for warm bodies with specific technical capabilities.
However, many companies are looking to solve specific business problems and might not know how. Simply hiring a developer who happens to know Ruby doesn't guarantee that the problem will be solved — it's a huge risk. It's sort of like saying, "all I need is someone who knows how to swing hammers if I want to build my wife and I's dream home."
Mitigating that risk means stepping away from the " freelancer" title and becoming a business consultant who happens to use e.g. Ruby to solve business problems. On your end, this is going to require less time spent thinking about the technology, and more about the path to solving the underlying problem at hand. From the perspective of a client, this is a much safer bet. And when there's less risk involved, clients are willing to spend more. And treat you more as a consultant. And you'll be happier, your closing rates will go up, etc.