The best way to have a good idea is to have a lot of ideas (Dr. Linus Pauling) and a little random outside stimulation, (the thought provoking kind) to ignite a tsunami of ideas hidden from you is all that's needed.
The biggest obstacle to training your mind to think laterally is your logical mind thinking this is sheer nonsense!
If there is an opposite of logical thinking it would be creative thinking and lateral thinking bridges the two.
Using Random outside stimulus is a very practical way to develop your lateral thinking skills but it won't be easy. Your logical mind will fight you tooth and nail.
Filling your mind with more creative thinking neurons will take time.
You can find out more about how to do that with Lateral thinking at ThinkTankSFI.com a new tool for the mind. This software for innovation is designed to unleash your creative power. Go check it out now!