What to read

Hello, I have a degree in Journalism with a minor in Painting. I am looking to study contemporary art and art history in Los Angeles and become a writer for it, like Carolina A. Miranda of the LA Times or Holland Cotter of the NY Times. Would you have any suggestions for how to go about doing this with no experience? I have never written about an exhibition and I cannot afford another degree for at least five years. I want to be mindful because I know that as a journalist, I can impact an artists' career with an article I put out, so I want to have my ducks in a row before I review an exhibition and publish it.