I sent out queries to agents who represented young adult fiction. I found their names online at agentquery.com and then researched them at Publishers’ Marketplace and online to make sure they would be a good fit. A friend clued me in to all of these websites—things had changed a bit since I originally queried my first book in 2004!—and that was super helpful. However, almost all of the queries were cold queries. I sent out 25-30 letters and only one of those was a referral (meaning another author friend had recommended me). And that wasn’t the agent who ended up representing me.
So—I am proof that there IS hope! You CAN be found in the slush pile!