I have a garage sale every year. The money I make used to pay for my daughters homeschool materials when they were younger, or other items we need or want. Last year, our sale went towards spending money for our trip to NYC (you can read all about that trip by searching NYC on the blog. I did a series).
I have been to many garage sales that are unorganized and chaotic. Needless to say, I do not stay at those very long (though I'm sure I could find some great treasures). Here is what I do to make mine successful and receive many compliments on how organized, clean and well priced they are.