Well, grandma had things from the early 1900's. We knew that they were valuable, and I had a few antique and collectible books, as that is an interest of mine, so we looked them up and found out the insurance replacement value, which is always the highest value. The highest value items we put on a special table with a sheet of paper by each item for the invited dealers (three counties, sent 50 invites, most came) and to sign and bid. It created competition. We decided that the highest bid had to be 50% of the insurance replacement value. Lower bids were accepted on a case by case basis.
We had two more sales until all the things sold. Those were public. The regular stuff, not high end, I priced it because my mom was too emotionally attached. She went back and changed a lot of things because she didn't want to sell them at all, let alone for a dollar. She marked them down on day two. We sold probably 90% of our things.
The most important factor in the success of our sale was displaying or merchandising the items. Nothing was thrown in boxes to root through. We covered every table with a tablecloth, we shined the silver and dusted every single item. Fabric or paper items (ephemera) we put in zip lock bags. We basically treated the items as though they had a higher intrinsic value than they actually had, and people could see that we respected the items and thus they paid a bit more.
After the dealers only show, we set aside a few unsold high ticket items and sold them on Ebay, then had two public sales for the remainder.
When I was a collector, I went to literally hundreds of estate sales over 20-25 years, and the ones which are priced by professionals are basically retail. I used to collect a lot of china, old linens, open salts and salt spoons, etc. I knew a deal when I saw one, and I never saw one at a professional estate sale. They were just too pricey. That probably sounds great when you are a seller. Yet if you over price items, then you end up with a lot of them left at the end of the day.
We had three separate sales in 1991, and we made enough to redecorate my grandmother's house for sale. It was several thousand dollars. Can't remember exactly how much.
Three years ago last week, we had a yard sale for my good friend whose husband died of cancer at 50 and left her without insurance. He was well-loved and we had a lot of donations. We had 30 tables which were organized by category, and we had six king sized sheets on the ground for clothing, which was organized by gender and size. We made $9000. It was the organization and the categories AND the advertising that gave us the success. I had it on my corner lot, two major streets, and I put a 60' sign all along the length of the house, and had it up for a week ahead of time. We opened at 7 AM and had more than 50 people lined up along the street.
Sorry, I think I rambled.