Cold messages to people in my field, do they work? (update)

I sent 11 messages on a professional network and got two replies. This is my first time dealing with any of this. I want advice, not a job directly.

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

I wrote three short lines: who I am, why them and a small ask for fifteen minutes. About one in four said yes.