2. Identify where people who need that skill spend time (meetups, clubs, slack groups, podcasts, discussion websites, mailing lists, etc).
3. Spend time at these places, delivering value, and pitching your wares. If you can get on stage to present, even better. A strong effort in a few places will usually beat a weak effort in many places.
4. Tell people you know that you are looking for gigs in your specific niche area.
5. Find agencies, others who do this work and let them know you're available if they get too much work, or get clients that aren't a great fit.
6. Most importantly, never be anonymous. This post is an example of a missed opportunity. Who knows, someone might have needed exactly what you're able to offer.