Okay, I feel like I'm cheating somehow by discussing non-fiction writing on a blog devoted to fiction, but bear with me. As any agent or publisher will tell you, it is far easier to publish and sell non-fiction than fiction. Our instant gratification society makes for a ripe market for information of any kind. For beginning writers, it's pretty easy to get published in non-fiction on the web, in small newspapers, in local magazines and newsletters. Once you have a few publications under your belt from smaller publications, move onto bigger fish.
Having your non-fiction writing published will give you more gravitas when you are searching for someone to publish your fiction.
How many times have you looked at the fiction submission guidelines for your favorite literary magazine or for a literary agent and realized that they want a listing of publications in which your writing has appeared? What agents and publishers want to know is that you've been vetted by other publications (and they think you're ink-worthy), and that you are a professional who can work with editors.
If you have been frustrated with rejection for your fiction, it might be time to readjust your publication plan of action. Building a platform as a non-fiction expert can take a while, but once you get those first few non-fiction publications under your belt, you will have new confidence in your attempts at fiction publication.
Here are a few helpful resources: