here is list of things that have helped me over time to do rapid development while keeping it structured
1. Clearly understand the goal and see it through the architecture/design pattern that the code is supposed to take
2. Know and memorize the basics and the system environment. If you are learning the system, have a handy debugger
3. Take a writers approach to coding. Breeze through your program while maintaining styling/design requirements. Add TODO's wherever you think more attention might be necessary but unimportant at the time.
4. Usually during development multiple problems need to be solved in the same function/file which creates frustrating distractions. If you face this constantly try meditation, it works!