Just write. And then write some more. And then when your fingers get tired and your eyes get blurry, write some more. Eventually you'll get good at it, and you'll find new ways to express yourself, your ideas, and your characters. Also, write for yourself. Don't worry about the money. Let agents and editors do that. And finally, be careful what criticism you accept. There will be one or two writers in your critique group who can help you, but that doesn't mean you have to listen to everything they say. Be careful, be choosy, and carefully consider what they are suggesting. Make sure it works, and then rewrite accordingly. Remember, you are the final arbiter of what goes on the page. It has to work for you first and foremost or it will never sound authentic.