Alternatively, if you are set to visit a particular site, either for leisure or work, pre-preparation will become mandatory. Such work will gradually assume into your improved photographer's mindset and you are then able to perform location assessment almost on the spot and be able to improvise.
Of course, the degree of improvisation is directly related to the type and availability of your gear list, which I believe is quite limited at the moment. Take for example Nikon's DVD show-casing Joe Mcnally's shoot at a ballet school, boat dock etc. Hey, he has to use up to twelve Nikon speedlights to shoot that boat dock scene! I am not too sure how many of you readers have a ready truckload of lenses, flashes, reflectors etc. So, pre-preparation with your very limited lenses (I have only 3 of them) and tools are wisdom well heeded.
If you have been to that site, its a bonus to run through the spot where you can take advantage of, for the objective shoot. If not, I am not too sure how much improvisation can we amateurs cook up on-site.