I live in the heart of a big city. If you're near one, finding out if they have curb recycling (especially in residential/small commerce zones) is a good start. In other words, if buildings and companies put their trash and recycling on the curbs for trucks pick up, you're golden. If you don't live near a big city, potentially driving through developments on curb-side recycling days would be a good start. One you start to find channels like this, your eye gets trained to see certain shapes, electrical cords, and the same types of things over time -- so what used to look like a clear bag or mound of "waste" starts to look like salvageable consumer goods.

If you don't have areas like this, you can go to thrift stores. I used to hustle 10-20 stores a day here until I tripped on this recycling opportunity.