Coding proficiency is essential to software practitioners. Unfortunately, our understanding on coding proficiency often translates to vague stereotypes, e.g., ``able to write good code''. The lack of specificity hinders employers from measuring a software engineer’s coding proficiency, and software engineers from improving their coding proficiency skills. This raises an important question: what skills matter to improve one’s coding proficiency. To answer this question, we perform an empirical study by surveying 340 software practitioners from 33 countries across 5 continents. We first identify 38 coding proficiency skills grouped into nine categories by interviewing 15 developers from three companies. We then ask our survey respondents to rate the level of importance for these skills, and provide rationales of their ratings. Our study highlights a total of 21 important skills that receive an average rating of 4.0 and above (important and very important), along with rationales given by proponents and dissenters. We discuss implications of our findings to researchers, educators, and practitioners.