I think everyone already knows that drawing and painting get a lot easier when you can visualize what you want the final result to look like.
What I'm wondering here is what people here do to kick-start their imagination.
In my case, I do a few things. Written prompts can be very useful - eg. SHINY HULKING CYBORG'S HEAD IS THAT OF SOME CUTE LIL' ANIMAL easily brings some images to mind.
I'll also commonly make some random marks on a page and turn it into whatever it looks like. I've been wondering about using Rorschach style ink blots as well.
Lastly, I've noticed I can "see" what I'm imagining a lot better when my eyes are closed, especially if I'm in a dim environment. I see tons of interesting stuff when trying to fall asleep. I've occasionally wondered it it would be worth it to buy some kind of blindfold - ideally one that block out all light.