First start posting. You have to make your mark so that netizens login just to read your piece. If your content is unique regularly, people will surely appreciate sooner or later.
I am telling you out of my experience with a mainstream newspaper, one of the largest English daily.
We always look for talents who are willing to write, rather than only think and never write. A lot of freelancers contact us asking similar question like yours, "how to start?" Though I must add, many of them have ended up writing for us since they had confidence in them.