Learn from some of the best. For example read and do the exercises of SICP followed by "Software Design for Flexibility - How to avoid programming yourself into

Learn from some of the best. For example read and do the exercises of SICP followed by "Software Design for Flexibility - How to avoid programming yourself into a Corner". The authors have more than 50y of experience and go through multiple iterations and refactorings of examples, pointing out good and bad aspects of the code.