Hosting a garage or yard sale is a lot of work, but it can also be very rewarding - you can feel good about your recycling efforts, and you will actually get money for the stuff that was just cluttering up your living space.
For me, the most challenging aspect of a garage sale is deciding what I'm willing to part with. I've found it helpful to keep a box ready at all times, and as I come across items I haven't used in a while, I store them for a future sale. And when the sale day comes, I try very, very hard not to change my mind.
Pricing the items can be very time-consuming, and setting a price when you have no idea of an item's value can be a bit tricky. Some people will tell you to set your prices high, and then prepare to bargain. I personally like low prices when I'm buying, and we always price on the low side when we're selling.
When I go to a sale that seems on the pricey side, I don't usually buy very much because I don't enjoy haggling. If you're running a garage sale business the rules are different, but my goal in having a sale is to get my unwanted stuff out of my house and into someone else's. Any money I make is a nice bonus.
Marking a price on everything is tedious, but it can be worth the effort. If you're unsure about an item's value, make your best guess and add Offers? underneath. Not everyone is comfortable with bargaining and if you have a suggested price listed, at least they'll know where to start.
I also make sure I have a box or two filled with free stuff on hand -- not garbage, mind you, but odds and ends that I can't imagine people buying. Crafters are frequently garage salers as well, and they very well be able to find a creative use for odd bits of hardware, empty CD cases etc.
Make sure your items are clean, especially if you're selling clothing, children's toys and kitchenware. And if you're selling an appliance or electronic item that needs repair or doesn't work, put a note on the item that says so. Most people appreciate the honesty, and someone who is knowledgeable may buy it and fix it.
