this other thread also has a cool map tool:http://www.uer.ca/...=1&threadid=123493
using those maps in coordination with driving around and just keeping an eye peeled is your best bet. or if you're ever in town/in the city always be looking for spots. whenever I'm a passenger in a vehicle (rarely), I have my face plastered to the window at all times lol
if you have a smartphone, it can be helpful to use google maps and just drop pins every place you find you would want to revisit or investigate when you got home.
word of mouth, in person or on social media is another great way.
some posts on here will give you enough tidbits and hints where a few easy google searches will show you where the location they shot was, and then the ball's in your court as far as determining if you want to go there, what your POE would be, etc. instagram and flickr can be really helpful too. use their search bars