Personally I lack creativity and have poor imagination so I kind of need other people to "guide me" or show me the way. My best ideas come from talking to other people, more specifically Ne ego types, where they somehow make me realize things I never though of before. A mind blowing experience. I absolutely love it. Oh, and taking other people's ideas and refining them. And ideas born out of necessity, like I have a problem and I need to overcome it so I'm forced to be creative. And interpreting observation, I notice something but can't explain it with current models and again I'm forced to be creative. Actually, those situations are where all of my ideas come from.
Ideas usually come to me when I am laying in bed at night in that stage where one isn't exactly awake or asleep; sort of that in between stage.
Other times I will wake up in the middle of the night and have such clarity of thought around something that I have to reach for my laptop and capture whatever was going on in my head before it escapes. I usually then find it hard to get back to sleep and find myself awake for hours trying to further clarify or make sense of my new idea.
In what moments and how did you get your best ideas in life?
For me, I find that my best ideas came from moments of strong introspection. Being alone from time to time was important as it allowed me to envision possibilities more easily. Another way I got good ideas was simply through debating with people about things... to the point where I would feel an "a-ha" moment and things would get clear.
In the past, the coolest Ni moments would come right before I would fall asleep, but generally I'd forget them.
Lately, when I'm alone just wondering, in the car, or good conversations that are low stress.