Extreme Programming
or XP (as it is called) says to pretend you are not a smart as you think you are, and wait
until this clever idea of yours is actually required before you take the time to bring it into being.

Extreme Programming Mantra :

"You're not going to need it"

Another Good Programming Practice Quote:

Some years ago, Harlan Mills proposed that any software system should be grown by
incremental development. That is, the system first be made to run, even though it
does nothing useful except call the proper set of dummy subprograms. Then, bit by
bit, it is fleshed out, with the subprograms in turn being developed into actions
or calls to empty stubs in the level below.

Nothing in the past decade has so radically changed my own practice, and its
effectiveness.

One always has, at every stage, in the process, a working system. I find that
teams can grow much more complex entities in four months than they can build.
— From "No Silver Bullet" [Brooks 1995]