I suggest that you start by looking where puzzle creators sell their own material.
If there are still puzzle magazines out there somewhere, like the magazine that is or was edited by puzzle maven Will Shortz, they do/did buy original puzzles from freelance contributors. Find some, study them for applicability to your needs, and see if you can get in touch with the authors through the magazine.
In fact, any magazine that publishes puzzles (whether or not that’s the main purpose of the magazine) might offer the same possibilities.
I don’t know how you might contact them if they’re online only, but I’m guessing there’s a way.