For me, what works is to just start writing as though I was talking to someone. Sometimes when I was trying to write I forgot that I was really just wanting to have a conversation by telling a story. When I write, I usually have no idea how the story is going to end. It goes where it goes. Just tell the story without worry about details. You can "fix" it later if it needs it, or maybe you'll just get past the block and tell the story right the first time.