The best place to list free classified ads these days is craigslist.org and backpage.com These are simple no-nonsense interface sites where you can list the property price, description and add images. The big drawback is you have to continue to edit and update your listing to stay on top of the listing system otherwise it will be more difficult for buyers to find you. You can learn more about how to do this through basic Google searches.
Your buyer profile can depend on what type of property you are selling, whether the land has been developed already, its location and market conditions, among other criteria. Is your likely buyer an individual looking for a lot for a new home? Or is your buyer going to be a builder or developer looking for land for their next project? Or is your buyer some combination of those, or someone different altogether? There may be different buyers for finished lots, rural acreage or a parcel of suburban land in a thriving new home market.