As everybody else is saying, practice practice practice. I'll add one extra on top of that: it's important to practice on real, complete, non-trivial programs

As everybody else is saying, practice practice practice. I'll add one extra on top of that: it's important to practice on real, complete, non-trivial programs that actually do something. Ideally it'll be a large project because that will give you practice in working with other people, API design, refactoring, testing, debugging, and reverse-engineering.