The key to fast improvement is to iterate as quickly as possible and have good feedback loops built in from quality sources. This is why sketches, outlines, designs, and rough plans are so important. The goal is gather as much feedback as possible, and then to iterate quickly. When enough information about the optimal solution is gathered at a particular level of granularity, then drill down into greater detail. It's essentially the gradient descent algorithm applied to life.
Kanban
I was browsing a list of tools and services for a lean startup a couple of days ago, when I noticed that many of tools implement a Kanban methodology. I had never heard of Kanban, so I took a quite trip over to Wikipedia.