This bit of advice was taken from Barbara's November newsletter: WRITING TIP OF THE MONTH --WATCH YOUR CHARACTERS:
Don't let your character's be windbags. You shouldn't lecture your reader, and neither should your character. And don't let them drone on for long paragraphs blowing and going and boring your readers to tears. And vary your sentence lengths. Make some short, some middle length and some longer. Keep your character on a short rein. When he starts to talk too much, haul him in.
Don't forget to let your characters think. Don't let them turn into mental giants, just a sitting and a thinking, but do break up long stretches of dialogue with a few thoughts. Let your reader get inside your character's mind. We learn what king of person they are by what they think. Sometimes what we say and what we think are two different things. So get inside their head and show what they are thinking.
Don't let your characters preach a sermon. I have just finished reading a book where almost every page reminded the reader that the character was a Christian. And let me tell you, I've been a Christian since I was thirteen, which was a long time ago. And even I got bored by the constant barrage of piety. I like listening to a good sermon. I've listened to a lot of them, but remember when we write fiction we write to entertain. Being lectured or preached to is not entertaining. And characters who are so holy and pious they would never dream of doing anything wrong are not only unbelievable, they are extremely boring. Let your characters live their faith, show it through their actions, but don't whack the reader over the head with your religious beliefs. You'll never reach them that way.