Steve Pavlina talks nicely about heuristics. Here is a snippet:
Heuristics don’t guarantee you’ll find the optimal solution, nor do they generally guarantee a solution at all. But they do a good enough job of solving certain types of problems to be useful. Their strength is that they break the deadlock of indecision and get you into action. As you take action you begin to explore the solution space, which deepens your understanding of the problem. As you gain knowledge about the problem, you can make course corrections along the way, gradually improving your chances of finding a solution. If you try to solve a problem you don’t initially know how to solve, you’ll often figure out a solution as you go, one you never could have imagined until you started moving.