I know this sounds like boasting, but I have never had a slow period. I have had to turn down gigs because I don't have time.
From my start as a freelancer I cultivated long-term relationships with customers who would give me a steady flow of work. Some of them put me on retainer, so they would have me ready to work when they needed something. A lot of businesses don't want to try to find a programmer or system admin under time pressure, or slog through Upwork or Fiverr. They want someone who will answer their calls and emails and deal with business needs without friction or onboarding, and without weeks of proposals, contracts, and email back-and-forth. I set out to establish trust and worked to understand the customer's business and IT infrastructure so I could jump on their needs immediately. I keep the friction and freelancer cosplay to a minimum.
Those customers referred me to other businesses, and before too long I had plenty of work and a reasonably stable income.
When I decided to travel full-time, and then move abroad permanently, I worried about getting work with US companies, so I signed on with an agency. And then I cultivated long-term relationships with those customers.
I know other freelancers who do the same thing. Building long-term relationships seems like basic good business. But I see people new to freelancing make some mistakes that lead them to churn constantly with customers, and fail to build relationships. I think that happens when freelancers think of themselves, and present themselves, as only providing specific technical expertise, on their terms. Customers need their business problems addressed -- the technology usually makes little or no difference to them. No business ever needs 2,000 more lines of JavaScript code in a week, but that roughly describes what a lot of freelancers sell.
The number one complaint I hear from prospects and customers: the last freelancer or dev shop stopped communicating, or took days or weeks to answer emails and return phone calls. Simply doing that better -- treating the customer with respect and care -- puts you in the top few percent of freelancers.
I have some articles about freelancing on my site typicalprogrammer.com. Free, no ads, affiliate links, popups, or nonsense.
Disclaimer: 10X Management represents me, but the opinions I express here and on my web site come from me, and should not get construed as endorsed by or reflecting the views of 10X Management.