"Heuristic is the art and science of discovery and invention" --Wikipedia:Heuristics
"The study of ways of steering your attention fruitfully, including the assumptions made about the Search Space you're exploring." --The Heuristic Wiki
In Computer Science, "a problem-solving technique in which the most appropriate solution of several found by alternative methods is selected at successive stages of a program for use in the next step of the program." --American Heritage Dictionary
- By distributing trials, errors, across 43F users, and reaping all discoveries (eureka!)
- By combating Procrastination. One of The NOW Habit's tools is "persistent starting".
Employ heuristics when you are stuck in neutral.
 Brute Force
The Heuristic Wiki says the simplest and crudest of all possible heuristics is brute force, or "checking every single point in the function space." Wikipedia calls this trial and error. Pragmatic Programmers call this technique tracer bullets.
If a) your target is moving, or b) you don't know all the factors, you use this heuristic. The antithesis is perfect plan up front, with no room for error or course correction. Progress inevitably slows as perfectionism begets procrastination, a 43F bad behavior.
The perfect brute force approach would be quantum force - trying all possible ways at once with the "right" answer popping up.
A terrific book on heuristics in mathematics is George Polya's "How to solve it".
A terrific book on heuristics in the social sciences is Andrew Abbott's "Methods of Discovery" Link
A terrific book on heuristics in multiple fields is "Simple Heuristics That Make Us Smart" Link