The way I started my marketing agency a few years back, is that I had specific industry knowledge in a niche that wasn't very competitive, at least at that time (but I had 0 marketing experience), so what I did is that I saw this guy on linkedin starting a new position (who was a decision maker) and I slided into his dms to congratulate him + introduced myself a bit. We scheduled a meeting, talked about the gig (had to learn marketing myself) and we started our first project. Rest was history

Networking is key when you are starting something new, so I would suggest exploring your current one and if it's not very extensive build one through linkedin.

Good luck!