Get a proper job. If you already have one, keep it and find a hobby that isn't writing. Chances are that you don't have what it takes to be The Next Big Thing in writing. And even if you have the potential, chances are that you won't make it, because writing/publishing isn't fair and quality doesn't automatically rise to the top.
Still here? Then write. Write one entire book and do it for the sake of writing. Don't do it because you think the book you start today will be finished in a month and will pay your rent the month after that. Just write, to see if you can get through an entire book (plus editing). You might realise that it isn't for you. Or you might realise that it is very much for you, but that you need something better than this first attempt before you start looking for an agent or think about selfpublishing. Or you might find that you now have one completed book with which you can try and tackle the publishing world. But first you have to write the darn thing. Starting ten different books has never made anyone a New York Times Bestselling Author. But finishing one has.