We had one about 10 or so years ago. It was fun. The problem was my wife underpriced everything to move it. It was the Saturday of a Memorial Day weekend. We didn't advertise, we live on a state highway with plenty of parking. We just started moving stuff out to the drive at maybe 8:00 in the morning. By 11:00 we were sold out. Everything was sold.
One woman lived down the road (up the hill) a few blocks. She paid but didn't have a way to move the corner cabinet she bought. So we put it in my pickup truck and I hauled it for her. Free delivery. My wife saw the woman last weekend - she still has the cabinet. And is happy.
If its junk, I toss it. If its something someone might like, I put it out at the curb. We've got hundreds of hillbillies a day driving past. Anything we put out vanishes pretty quick. Even scrap metal. Go figure.
When visiting other peoples garage sales, if you see anything hunting or gun related, ask questions. Be very polite, but ask if they've got any more hunting/shooting/gun related. Many women don't even consider that anyone would like that kind of thing. Some don't even know if its legal to sell the stuff. But a polite question sometimes reveals a lot of stuff underpriced.
Take special notice when you see reloading dies!!
On the issue of your own garage sale, don't leave any hints you have guns or shoot. Its an invitation for thieves.