Any good resources for learning linkedin marketing / outreach?

Hi everyone! Kind of new here have been lurking for a while.

I'm wondering if anyone knows of good resources blog posts, or courses for marketing on linkedin.

I'd like to use the free month trial of their sales navigator plan to try and cold message potential customers. At this point I don't care to make a sale and more want to get quick feedback from customers / potential customers.

Anyone have success with using linkedin this way?