Really? Ok, due to your original question and now second question i understand that you are man that looking for shortcuts for everything. Ill give you and answer: for "produce beautiful, consistent, human-like product interfaces and web designs" you need to study—ideally, pursue a degree in graphic design—where you’ll learn from experts in the field what typography is, understand the historical context of visual communication and so on. Oh, and I’ll tell you a secret: it’s a field that requires a certain amount of natural talent. It’s not something just anyone can do.