When facing a problem the usual "envy" is to create a big solution that seems to address every problem.
But in real life, you'll soon realize that's not that easy! Small problems go along your way and transform that wonderfull piece of solution into a not so perfect one!
I found working with small steps the better way to achieve things. Taking small requirements and adding them one by one is the best solution.
The Toyota production system really captured that spirit.
The same principle apply to Software has been discribe by Mary Poppendieck. (Excellent article: Principles of Lean Thinking).
You can also find a definition of Kaizen at wikipedia.