Education, get all you can. Knew an unfortunate who lacked education and became a permanent co-pilot on DC-3 and CV440 until retirement. Johnny Robbins by name, flew everything with wings in New Guinea before the war, during the war it was Captain with Guinea Airways. With the coming of peace the authority required the passing of exams in order to hold an ATPL, and Johnny just didn't have the mathematical skills to get through the exams.