Use it when you cannot find a solution by other means.
Use it at the end of a creative session, to plant the need to solve the
problem in your subconscious.
How to use it
Immerse yourself in the problem
Immerse yourself in the situation, exploring all angles and thinking in
detail about the problem.
Go for a walk
Now do nothing or otherwise distract the conscious mind to leave the
problem thinking to the subconscious.
Let the Eureka moment happen
The subconscious will eventually reward your patience by popping an
idea into your conscious mind some time later. When this happens is not
very predictable--hence the classic 'three Bs' are whilst you are in bed,
bath or bus (note how these are when you are relaxed). In order to catch
these slippery ideas it is a useful practice to always carry pen and paper
See if it makes sense
Once you have the idea in your conscious mind you can now check to see
if it makes sense and is useful to you. If not, you can thank your
subconscious and ask for another idea.
I a having problems inventing a new form of loudspeaker. I have studied
the technology from all angles but can't find a solution for a thin-panel
system. So I just forget about it. I go for a walk and then do some other
work. That night, I wake up with a great idea...
How it works
One of the first modern descriptions of creativity is in Graham
Wallace's 1926 book 'The Art of Thought', where he explained the above
stages as 'preparation, incubation, illumination and verification'.
What is particularly interesting about this is the utilisation of the
subconscious mind to come up with creative ideas.