I find digital consultancies / agencies always have spikes of work and they need folks to join in for a couple of weeks or months. Just make connections there - send in your cv, ask about part time positions etc. Agencies usually have one or two recruiters they trust so go and make friends with them too, chances are that recruiter is connected to a few other agencies and so forth. It’s all about networking though, and finding individuals that are reliable.
Bear in mind, to address the point about making money "quickly", that if you go direct to a digital agency, they will expect you to do a month's work, and then for you to send them an invoice with 28 day terms, and then they will pay when it pleases them to do so. So that might well be two months between sitting down at a desk and money actually appearing in your bank account - or it might be longer. (Speaking from experience in London.)
(If you go through a recruiter, you might be in a better position, because sometimes recruiters want you to invoice weekly and sometimes they pay more or less on receipt of the invoice. And sometimes they don't, of course.)
I had been working as a web dev (full stack) for some years, so the freelancing gigs I found were mostly web programming. One gig was for my ex-employer, other one was for other company. Of course you need to have some selling skills as well and know some people who need to do business.
During that time app stores were a relatively new thing, so the products I was developing were apps. They started making a decent revenue after 2 years if I remember right. The first year I didn't make about any money. I had very low-cost lifestyle, and cheap rent in a tiny apartment, which helped a lot. If I would have kids or some expensive hobbies it would have been much, much more difficult.
