I've never run one but I've been going for years and 'gotten in' with a few estate sale company owners.
Heard complaints and gleamed some wisdom. Best I can offer is their comments and things I've dealt with as a buyer....and mistakes/hassles I've seen at privately run estates.
So.....
First off, give yourself time. Most companies have several people working 3-10 days before sale. Talking hundreds of man hours to organize, price, set up......
Make sure there is some sort of path. In one door, cashier out back door. Or round thru back to front door and cashier there. People tend to enter and away from cashier first. Don't allow any unmanned exits.
Expensive stuff and smalls, jewelry, silver and all that placed by cashier. People steal.
Don't throw out anything. You never now what people will buy. To you it may be a pile of broken broom handles, to someone else its items for a DIY project. However, do clean. Vacume. Air out/fabrezz. Clean sink. Out the garbage. No one wants to hang about in filth. Longer they stay, more they see, more they buy. I personally like cookies and coffee/cocoa offered too. Happy people, jacked up on caffiene/sugar, are more likely to buy.
Go thru everything. Pockets on coats. Back of silverware drawer. It's like a storage unit. You usually find the diamond ring in the bottom of Xmas wrap, not in the safe.
Use any shelves and tables possible. Spread it out. Tho nothing wrong with a "digger sale" if a room, garage or shed is just piled. But be sure to have staff about to deter theft and price item.
On that, make sure everything is priced. Most wont ask = won't buy. And all staff should have identical tags to mark unpriced items you missed.
Clear one room for putting things that aren't for sale. Have a shelf or space by cashier for people to collect goods they want. Put heavy tape and sign on any door and drawer you don't want open. Overkill is good. People will go thru everything! They will trash the place and disorganized stuff which makes it harder for others to see whts there.
Hang a sign up list the night before (securely tape pen to it). Follow list! Call a name, no answer, cross it off. They come later, to bad. The list is god. And size the house. Only let so many in at a time. You'll be overwhelmed plus having 30 in line to pay means other can't get around to look. Let them stand in the rain and enter when others have left.
Prices? 100% first morning. Then up to you on mark down. Most do 100% the I first day, 30-50% the next. Really depends of the items, what has sold. Prices should be below retail, competitive, even priced-to-sell. But no shame marking high end goods at retail and negotiating price the second day or taking bids.
And advertise! Estatesales.net 2-3 weeks before. Craigslist a week and agian a day before. Signs on street, down the street, at closest main intersections the day before (check city codes)
Post disclaimers. Not responsible for injury. Bring own packing, boxes, lifting/carry help (you don't want our people wasting time moving furniture when they should be watching for theft or priceing items). Post if ou except credit cards (most only do over $100 and charge 3%). Post if you charge sales tax but also if you DON'T. If you charge sales tax post if business licence owners need to pay, if not be sure to get copy of tax exemption. Copy, not just look at it.
I could go on forever.....if you have a specific question/concern let me know.