Forget about writing a story that has anything to do with you or your life as a struggling writer. The immediate "tell" of a novice writer in Hollywood is someone who is peddling a screenplay based on their lives. This is because these movies are usually small and intimate, and there are a million of them floating around Hollywood at any given time. The only exception is if you had something extraordinary happen to you--you survived a plane crash, lived on the ocean for 3 months, ended up floating into a terrorist country and were ultimately saved by American soldiers.
Develop high concept ideas that the public would love to see. A high concept is something that can be pitched in one line where you instantly "see" the movie. For instance "The 40-Year-Old Virgin." By simply saying the title, you "see" the movie. You then can follow it up with, "it's about a hapless 40-year-old who could never succeed in relationships and must overcome his fear of women and relationships to find true happiness." Another example would be the Jim Carey movie "Liar, Liar." It's about a lawyer who can't lie. You instantly understand how the idea is inherently funny because lawyers are notorious for lying.
Read as many good screenplays as you can that are like your high concept. You must be a great student before you can master your craft. And remember not to read mediocre material. If a movie was just okay and you learn from it, then your movie will be the same. You must learn from the masters.
Write your script. Now comes the actual hard part of being a writer, the taxing toll of pumping out 120 quality pages.
Travel in circles of people who can read your material and give you effective notes. If the coffee guy at the end of the street is the only guy you know, you need to know more people. He's not going to be able to submit the script to a studio or agent. Get out on the town and start meeting producers and agents. Also strive to meet the highest end people in the business. It will be more difficult to build a meaningful relationship with them, but that relationship will be more effective when it's time to sell your screenplay than a relationship with some low level players.
Re-write your script from the notes you receive. Writing is the art of re-writing. That doesn't mean you must listen to everything people say about your script. But if several people in the business read your script with similar notes, then it is time to address that note. The tricky part of this is that it is still art, and therefore until it's in the hands of the people who can cut the check, you must guard against simply re-writing for re-writing's sake.
Refuse to take "no" for answer. Again, this doesn't mean you need to be rude or unpleasant, it just means that if being a writer in Hollywood is your dream, stick with it. In a town that is saturated with people trying to make it, perseverance can be your best asset. Just make sure that you are constantly improving yourself and your writing.