There are a few solid ways to previsualize. Any street shooter worth his sore feet should know about this. One way is to SEE in your mind a scene and the image you want to make. This works from the memory section of the street brain. Your out there on the street and your street brain is recording scenes even if your not working them at this moment. Then you go to sleep and you dream about the scenes from the day. when you go out again, those dreams could manifest into a photo because you dreamt about working them.
Another way is to have whats commonly called….The Decisive Moment. Really what that is, is the previsualization that a photo is being borne right now, right in front of you. You must be prepared for this experience at all times.
I was walking south on 18th street just below JFK and I saw this window. Suddenly my heart started skipping beats….my pulse raced….I struggled to maintain my composure…..I was still over 50′ away…as I got closer I started to raise the camera….
I got to where I should be without looking at the screen….the guy moved his head in and out and everytime I could see his entire face….then at one point…..
his head was there and his face disappeared and….CLICK!