Declutter like crazy - for tips on decluttering check out
www.flylady.net (though she does not advocate garage sales). Include everything in the sale (with the possible exceptions of underwear and used makeup, though I have heard of doll makers buying used makeup).
Definitely price everything beforehand (with stickers and tags).
Price things cheap - for my sale, most items were $1 or less, we made $500 with no big ticket items. To move books, clothing, and toys, consider 25 to 50 cents each.
Don't bother with newspaper ads, but do make good signs (all in the same color like pink or yellow, with big BOLD letters (doubleback over your handwriting with the marker), all it really has to say is "Garage Sale, Sat 9-2, Address" and a HUGE arrow pointing the way to your house). Be sure to take down the signs later.
Have a free pile and put it near the curb so passerbys will see it, it gets them out of their cars. I put magazines, half-full bottles of shampoo and household cleaners, pens (they multiply in my house), broken appliances, fabric scraps, and all kinds of stuff in it.
Definitely have bags and boxes to put people's purchases in, it is also nice to have newspaper to wrap fragile stuff in. People really appreciate this and will buy more.
We also sold sodas and candy bars and netted a nice profit.
For lots of great tips, check out
www.yardsalequeen.com