Reading about interesting locations is certainly a part of it. I've found that if I research the local geology, I can find noteworthy sites to think about placing an EC. Also, sometimes just stumbling upon a cool place with geological importance sparks a sense of creativity and willingness to create an EC (ie: https://www.geocaching.com/geocache/GC9W5KX, https://www.geocaching.com/geocache/GC9YPMV, and https://www.geocaching.com/geocache/GCA038C).