How to connect with a new audience?

I've seen the advice that you can talk to an audience and solve their problems.

How do I approach them?

Let's take "freelancers", for example.

How to approach/talk and talk to these "freelancers"?

Should I just go to r/freelancers subreddit and mass message everyone?

Should I go to twitter and search "freelancers" and cold DM everyone?

Most importantly, how should the cold message look like?