Write as much as you can. One script may help you break into the door, but producers, agents and other people in Hollywood will want more content so they can see your future in the business. Keep writing and constantly coming up with ideas that you can turn into scripts.
Enter contests and festivals with your script. If your writing is good enough, then you will eventually place in one of these contests and get your name out there. Oftentimes the top winners have their scripts sent to various production companies that could buy or option your script (see Resources below).
Learn the screenwriting format and master it. You could have the best story, but it could get tossed out the window if it is formatted improperly. Purchase a screenwriting book or look up the information online to learn formatting tips (see Resources below).
Purchase a professional screenwriting program. Movie Magic Screenwriter and Final Draft are two of the most popular script writing programs and using them is essential, especially if you get a permanent job in the business (see Resources below).
Register all of your work with the Writers Guild of America. Many production companies will not even look at your work unless it is registered with the WGA. Each piece of work costs around $20 to register and will receive a unique serial number to include on script title pages (see Resources below).
Send out query letters to agents. Getting an agent is one of the most important steps to becoming a Hollywood writer. Query letter should be personalized and handwritten, and you should not send out a script unless the agency specifically requests it. The easiest thing to do is to include a few log lines and a treatment of your script (see Resources below). A log line is your whole movie condensed into one sentence. A treatment is a 3- to 12-page summary of your movie.
Include a self-addressed return envelope for an agency's response. A response can take up to a month, and sometimes agencies may not even reply back at all.