Read books, magazines, blogs, Twitter feeds, and websites. If you want to go deeper into a subject, consider joining a mailing list or newsgroup.
Always try to work with a mentor, as being the top guy can hinder your education.
Not everything you learn has to be about technology. Learn the domain you're working in so you can better understand the requirements and help solve the business problem.
Most experienced programmers have learned that a good API follows a consistent level of abstraction, exhibits consistency and symmetry, and forms the vocabulary for an expressive language.