When I am doing a household purge, I offer things I don't want or need to my friends on Facebook, sometimes for free or a nominal price. I got rid of my futon mattress that way; still in pretty good shape but I was not able to sleep on it comfortably. I posted it on Facebook and a neighbor up the street took it to make a couch for her guest room after she bought a futon frame off Craig's List. I was happy to help her, and it was an easy way to get it out of the house so I could get a real mattress in.
Other stuff that I know has value I sell at our local consignment shop. Every few years I pay $15 for a year's membership and again, when I am ready to purge yet another layer, the more valuable stuff goes there. This summer when I was off work from the broken foot i helped my mom go through her myriad jewelry boxes and weeded out a lot of items that she no longer needed. Many pieces had vintage value and I know she will get money for them. I recently made $68 by selling two coats and some jewelry to a vintage shop on campus - one jacket was a fringed '70's suede that a friend gave me when he moved out of state, and the other was a long wrap coat that had a vintage feel to it that I acquired at a clothing swap. I wore it once or twice and decided I was done with it. I was thinking maybe I'd get $40 or $50 for the lot, so I was pleasantly surprised when the owner of the shop wrote me a check for $68, seeing that both items were "gifted" to me!
The moral of the story here is, I don't make it too much of a time consuming effort to sell items, but I have a good instinct about the value of items and current going prices for them, and knowledge of outlets in my area to sell things at. I don't bother with yard sales anymore, especially in my neighborhood where people try to bargain down the price of a $1 pair of shoes. Other stuff that I am done with at home, or clothing I am ready to give up just goes back to the thrift stores, from whence they came!