disclaimer: i've only been doing this for a couple years...but it's gone pretty well. i've written this more like a story than direct advice, because i think all the twists and turns are relevant.
i went straight from college (dropout) into the consulting world right before COVID hit. i gave myself a year to get the consulting business going, and if that didn't work, i was planning to get a "real job."
i started off by leveraging my existing contacts in the software world: mostly a couple internships that I'd had (one before my year of college, one after). the first few months, i was only working for those two places while i tried to figure out how to expand. i started a blog [0] at this point -- it was mostly nontechnical content, but helped me demonstrate that i'm a sane person and a reasonably good communicator.
i started replying to the "Who wants to be hired?" threads here on HN and got my first couple (small) independent contracts there. then a family friend who runs a high-volume used book business needed his whole inventory/order management system redone from scratch, and i was a) cheaper and b) a known quantity, so he hired me. you can interpret this as me getting lucky, and in some sense it is, but i strongly believe that luck favors the prepared. i certainly wouldn't have gotten that gig if i hadn't been prepping for it, hard. this is when i started to raise my rates.
(you've probably seen this repeated endlessly on HN, but it bears repeating: raise your rates. raise your rates. and then raise them again. to match $XX/hr as a FTE, you need to charge at least 2*$XX/hr as a consultant. ideally a lot more.)
i spent tons of time reading HN and twitter, and responding to anyone who was doing something i found interesting. i went into these interactions with no expectation of getting work out of it -- i just wanted to meet people who were working on cool things. a few of those interactions did turn into work, and one person i met is now one of my best IRL friends. crazy.
at some point, i had to learn about a new amazon service (the Selling Partner API) for that bookstore project, and discovered just how badly documented and tested it was. after a couple months (!!) figuring out how to use it properly, i wrote a few blog posts about it, and people started hiring me from my blog (and now, my OSS SP API library [1]). between that, and a few of those people i talked about meeting via HN/twitter/etc, i've kept busy for the past 18 months. i actually just hired my first part-time employee, which is exciting :)
i think the three biggest things that have made me a modestly successful consultant are:
1. focusing on people over everything else. if you're a consultant, you're a salesperson, and in my experience just being genuinely interested in other people is the easiest and most effective form of sales.
2. writing online. it's cliched, but it works. you don't need that many people to see what you've written for it to be worth it -- i've never gotten more than 150 views in a day on my blog, and usually it's way less than that, but that's been enough to have plenty of work.
3. raising my prices ;)
i make a lot less money than i might by working for FAANG/etc, but i have total time and location freedom, i don't work a ton, and i really enjoy running my own show. ymmv, and good luck :)
[0] https://jesseevers.com
[1] https://github.com/jlevers/selling-partner-api