I get away from the computer. I take my notebook and sit in my "thinking" chair and ask myself "what am I trying to say?" Then I begin writing to myself, knowing only I will ever see it. I just keep writing about what I'm trying to say. Usually, about five or six paragraphs down I'll see something I can begin writing about. It's like a break-through happens while writing. Also, I don't know why, but deep breaths before writing helps too.