One thing that beginning writers often fail to understand is that good writing doesn't just happen. It takes practice. It takes loads of rewriting. I preach this over and over again in my classroom, but sometimes I think that they don't take me seriously because I'm their teacher and what do I know?
Maybe if they heard it from an ACTUAL writer they'd be less hesitant to believe that I'm just making them do more work that they don't want to do: