When I did it, I did a lot of advertising on places like craigslist. I got zero leads from that kind of advertising. It was only when I advertised on Facebook that the hits began to come. And what really sucked about it was that it took me a while to find client one, and as soon as I found client one they connected me to the next five, and those five connections made the next 20. So I was hoping for work for a while but when I finally found it I had to start turning people down. You will find very quickly if you’re going by word of mouth that tax help is a must, and I got pretty good at doing taxes through that which is a useful skill.
I would shamelessly promote to people you know. Be proactive and be persistent and have perseverance. It will come. Being an accountant by trade is a lot like being a plumber or an electrician; lots of folks will need you at some point, you just have to let them know that you are the one they can call, or to remember you when they make that call.
it turns out that I personally hated that kind of work, but it did help a transition between two jobs and I still help some of these folks from time to time from an advice perspective, and it helped expand my network in the end.
Good luck.