"cut the crap and read ... and pass the chocolate!"
In other words, don't waste time explaining yourself before you read your piece to the group. Don't apologize if it's a first draft (remember... you can't edit nothing). Don't give a long-winded spiel with the entire history of your piece.
You know what? It's a good rule when you get behind the podium at a reading as well. Too often I have heard someone spend longer prefacing their poem than reading it.
Beware. It can suck the life out of the piece.
While some writing may need a small piece of context, most can stand on its own. You do not need to justify yourself before you share your work. You are a writer, and you have every right to be heard. It's natural to be nervous if you are inexperienced with reading, but your audience wants to hear your work. Go for it. Plunge right in. You don't need the verbal equivalent of throat clearing.
Trust your listeners. Have faith that your work stands on its own merits. Don't hesitate. Cut the crap and read.
And reward yourself with some chocolate after the applause dies down.