For myself, I just notice places as I drive by or get told by friends, generally you can chat to th eright people and get acess without a major problem bu then again it depends on the location
For city locations, I tend to go wandering around by myself with a camera. If I find somewhere interesting, I start snapping away for reference as well as folio shots. Good old fashion legwork :)
Other than that, it's pretty much as Dave has mentioned. Also something you might want to try is to just pick a suburb and go there for a few hours and see what you can come up with.
There's nothing like setting a day aside for going out and scouting locations. Bringing your iPod and just walking, driving, exploring. It's like being a kid on a treasure hunt! ;)
It doesn't even have to be a full day (although this would be SO refreshing!), just a couple of hours per week would do, instead of meeting friends for coffee or going home early... Just by keeping my eyes open and really "seeing" the environment around while driving. When scouting, then everything else disappears and the world transforms to a huge potential stage where the next click will be heard!