Read a book to learn about the standard formatting for screenplays. Many books are available, including Syd Field's "Screenplay," which is considered to be essential reading that delves into formatting and the three-act structure of screenplays.
Format your screenplay according to industry standards. Most agents will not read screenplays if they are not in standard format. By strictly adhering to formatting guidelines, you will increase your chances of getting an agent.
Research agents who represent screenplays and screenwriters. These are often different from literary agents, who focus on books. Compile a list of agents who represent your type of script. You can find listings online and in market guides, which are available in bookstores.
Read agency guidelines to find out what you should include in your submission. Some may require a brief synopsis, while others might ask only for the first few pages of your screenplay. Always follow these guidelines, otherwise your submission will not be read.
Write a cover letter to include with your submission. Highlight any relevant information or qualifications. For example, if you wrote a screenplay about spies and have a background in counterintelligence, briefly mention this. Make your cover letter brief and to the point, and it should not summarize the screenplay.
Submit your screenplay to a number of agents. They may pass on it or they may ask to see more material, a process that may take several months. Agents may ask to exclusively read the entire script, which means you agree not to send it to other agents until the first agent has had a chance to decide whether to accept or pass on it.
Repeat the process with more agents, editing your screenplay if you need to. Agents may suggest changes to make the screenplay more marketable. Consider their suggestions.