Cool! That's a really great type of business to be in when you are first getting started because it reduces the "all or nothing" trick of employment as a developer.

I did some of this myself, and I know @jess did too.

Here are some thoughts. They are not dependent on one another. Don't think you need to do all of these things, but some of them might work.

• It helps to have a platform niche. I used to do Wordpress development and could position myself as an "expert" (even though I never really was). I mentioned Jess because she did Squarespace development and it followed about the same pattern. It helps to find newish platforms where there aren't as many entrenched experts. (I'm not totally sure that matters, but that's my gut).
• Don't be afraid to take on small expenses. I used to run Facebook ads to find clients for my little freelance Wordpress business. It was a great source of leads and I think it added a small amount of legitimacy to the inbound leads. Don't just start spending money willy-nilly, but don't think that it is not an option to experiment either.
• Charge what you're worth. Don't rip people off, but charge more than you think you should. You'll be treated better if you charge more, and it will let you sink your teeth into the work.
• Build on your success as you go. The first project will be the hardest to come by, but as you go you can highlight your best work and use it to get the next client. Don't even link to your earlier or weaker work most of the time. Quality over quantity.
• Try to offer painkillers and not vitamins. If you can specialize in a type of problem people are desperate to solve it's better than doing something that's more of a nice-to-have.
• If you notice a demand for one particular type of work, focus on that, even if you know you could do all this other stuff. Take what you can get and build momentum around it.
• Exude professionalism at every stage and treat your service with an "agency" quality. Sure, it might just be you, but being an "agency of one" can help you sell yourself. You can still put your name on the masthead in any way you want, but put your work and services front and center, not necessarily yourself.
• Focus on delivering something new and fresh to every client, and then hustle your way to the next client. I said you should charge more than you think you need to, but you may also need to do free work just to get something under your belt (if you don't yet have the right stuff)... But use it all to create compounding effects, while constantly moving on to the next one.

Hope this helps! It's not easy, but if you commit yourself to this you will either succeed or you'll fail in a way that will help you towards whatever the big success ends up being. This experience will provide skills you can bring with you at every stage of your career whether as an employee or entrepreneur in the future.