If I catch myself blushing I can often think my way out of it, switch of the negative thought that is causing it. A big part of it is to not care about blushing either, else it will compound. It always feels worse than it looks
Things sometimes seem worse than they really are. Someone in a play I was in said that holding your arms straight down by your side feels silly, but it does not look silly. I looked at him later when he did it and he was right.