5. Which technique to choose?

Inversion is fun, effective and easy to implement. It's very useful on "blocking" subjects that don't encourage the release of the imagination (safety, for example), or on subjects on which we've already looked in vain.

The subject must lend itself to this: in the wording, there must be a verb that can be inverted: attract, improve, increase, reduce, lighten, lengthen, etc.

This technique is also useful for "warming up" a group before using another technique such as analogy.

Analogy is more difficult to implement, and requires already-trained participants. It is well suited to "difficult" subjects requiring a high degree of innovation, with strong constraints; if you can distance yourself sufficiently, it is then very effective.