Years ago, I took a writing class with a guy named Tom. He was the best writer in our class. Our writing teacher even recommended Tom to his agent. (Something he didn't do for me, or anyone else in the class for that matter. Not that I'm jealous. Not that I'm going to point out that I'm the only out of that group who got published, as far as I know. I'm not that petty.)
In his book, Tom had the best trick for revealing some facts about a character. Several characters were talking at work, and one started imitating the main character in an exaggerated fashion. The dialog was completely believable, good natured - but true - teasing between two people who knew each other well. It was such a wonderful way to tell the reader about the main character without having it come as a narrative.
Since then, I've stolen that device a couple of times.
A year or so later, I ran into our teacher and asked about Tom. He said his agent had passed on Tom's book, and so had a few other agents, and Tom had gotten depressed and stopped sending it out.
Lesson 1: Steal. Steal judiciously, but steal. Techniques particularly lend themselves to thievery.
Lesson 2: Keep writing, keep trying to find an agent, keep believing in yourself. I say it again, Tom was a better writer. Tom should have been published. I don't remember his last name, or I would Google him. I hope he did get published.