What causes a facial scar to turn red?

Last October I had an overgrowth of dead skin removed from my upper nose. It left an incision about 1/8th of an inch, triangular shaped, and I had to keep the incision dry. You can still see the incision mark, it's an indentation in the skin, and it turns red very easily and often. What can I do to heal it over and stop if from turning red?