Freelance Writing

I found the lesson on freelance writing very interesting because I have always toyed with the idea about writing freelance. I never did the writing because I had no idea how to get my ideas to a publication and I'm not confidant about writing for a publication. This lesson taught me what I need to do should I decide to freelance write. The proposal letter I wrote for our class assignment is actually an idea I have been wanting to write for a regional magazine for many years. Maybe I will actually do it now that I know what to do. The question I have is what degree of expertise does a freelance writer need to have about a subject, or is diligent research enough to write an informed article?