It’s true: most signed manuscripts reach editors through agents. Frustrating, yes, but it cuts down on editor response time with submissions. Agents essentially screen manuscripts for editors, who know that if an agent shows them something, that project is likely of interest. Reviewing random submissions means losing time sifting through manuscripts that aren’t even in the editor’s realm of interest, hence the popular “no unsolicited manuscripts” rule.
To get your agent, go to writers’ conferences, retreats, and regional meetings, because the agents who speak at those events usually extend open submission invites to attendees. And when you go, always pay for critiques with the agents. Face time is invaluable. Be polite and firm but not pushy. That means no shoving manuscripts under toilet stall doors. Don’t laugh, that really did happen to me when I spoke at a conference. Ever polite, I called through the door, “How about if I wash my hands first?” I’m happy to say, the writer let me.