Of the Big Five traits, conscientiousness consistently played the most important role in academic and professional success, Charles Murray explains (in Human Diversity: The Biology of Gender, Race, and Class), with openness in second place:
Poropat reported effect sizes for them of +1.14 and +0.96 respectively, far larger than those for agreeableness (+0.19), emotional stability (+0.36), or extraversion (+0.23). In addition to its value for academic performance, conscientiousness has also been found to predict job performance, salary, promotion, and occupational prestige. These findings make sense.