Full time freelance consultant here, specializing in product strategy and early customer acquisition. This should apply to your situation as well. What other people have said in this thread is mostly accurate: consulting is 100% about client development, and 70% of client development is doing good work for the clients you do have, because almost all your clients will be word of mouth.
But, that doesn't answer the question of how you get your first clients. Here's what I suggest:
- Start networking. Set up meetings. Lots of meetings. With everyone you've ever met, at all levels. Depending on who you are talking to, float the possibility of leaving your current job to 'see what opportunities are out there'. In some cases you can be more specific ("I want to go freelance"). In other cases you can be more declarative ("I am freelance now.") The purpose of these meetings is connecting with people, most of whom you probably haven't talked to in a while. The purpose of networking is making friends. You want to catch up with people and slip into the conversation that you're going freelance now or already are. You don't have to ask them for work; work will find you. It's important to realize that networking is ultimately about increasing the number of nodes in your network so when one of your nodes has a friend who is looking for work, your name is top-of-mind for a referral. The best sales come from INCOMING connections, not outgoing ones. Engage in your networking activities to maximize your incoming referrals.
- How do you start networking? I'm sure you have friends at work who won't go blabbing to management about your desire to leave your job. Ask them to connect you with people because you're looking for new opportunities. You don't even have to mention consulting--saying something like "I've been working here for a while, and I'd like to see what else is out there. Do you know any people I can talk to who are doing something interesting?" will work. This will be your initial word-of-mouth funnel that will lead to clients.
- Use meetings as a way to get to more meetings. It will come up naturally in the conversation. "Oh, the work that Acme Inc is doing with data warehousing is really interesting. I would love to find out more about that!" Make the goal of every meeting to get a new meeting.
- Go to networking events. Not coding meetups, where you'll only meet other engineers, but boring industry-related networking events where you'll meet real companies who can hire you. If you work in a real estate tech company, go to a real estate industry event. Go to tech industry events like Techweek. When you're there, meet people. Make friends. Make sure they know what you do, and you know what they do. Get their business cards. Follow up with people you like. Set up more meetings. Etc, etc.
- One thing that could work for you: there's nothing wrong with taking job interviews, especially at small companies that can't necessarily afford to pay for a full time person. If you establish yourself as a freelancer and do a good job, it's easier to get freelance work at higher levels. Many companies who bring you in for an interview will be responsive to something like "I can't really take on something full time right now but all you need to do is deploy a new framework for your site, so I can do that in two months for $X,000. How does that sound?" Boom, your first fixed bid contract.
- In summary: you should spend 100% of your time outside your job networking. I promise you will get clients quickly.
Those are some DOs. Here are some DO NOTs:
- Do NOT try to sell to anyone in your network. This seems counterintuitive, but you will almost NEVER hard sell consulting services to someone you already know. Networking is not about sales; networking is about making friends, and you will LOSE friends if you try to sell freelance services to your friends. Instead, like I wrote above, maximize incoming connections. I guarantee you will meet with someone and halfway through the conversation they'll say, "hey, I have this friend who's building an X, can you help with that?" Boom, instant sale, and the best part is, their friend is referring you so your reputation will start warm rather than cold.
- Do NOT hire a salesperson. You are not a company, even if you have a logo. Your company is YOU. Clients will hire you because they trust and like YOU. Until you have 10+ clients full time, you will be indistinguishable from your firm. There's a reason why even major consulting firms (McKinsey, Bain, LEK) are named after their founding people, decades later. Oh, and by the way, those firms don't have salespeople either.
- Do NOT waste time on marketing, research, positioning in a market, etc. Your market will be determined by your unique skillset and your referrals. Treat this like a MVP startup: let the customer guide you to a product-market fit. You can spend 2 months building a website that no one will visit, or you can spend 2 months building a network of thousands of people. Choose the latter.
- Depending on your cash situation, I wouldn't quit your job yet. Until you have a client or clients willing to pay you at least half of what you're making now, pretend your current job is your current client. Use it as an opportunity to get new clients.
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TL;DR: Spend all your time networking until you have clients. When you have clients, do amazing work and they will introduce you to more clients. Never try to make a sale. Sales will find you. Good luck!