Green Light thinking means coming up with ideas and not judging them, just coming up with ideas and writing them all down.
After a good nights sleep, you then apply ‘Red Light’ thinking to your ideas. Go through it and knock out all of the things that you didn’t judge when you were writing your list but are just not appropriate. But remember having these ideas, that may not be appropriate themselves, probably led you on to other thoughts that you wouldn’t otherwise have thought of and some of these you will keep.
The idea is to get the critical part of your mind out of the way while you answer the questions you need answering. Just thinking about what you would do if you could do anything and then write it down. Then thinking about ways you would achieve that.