Note: This may be long. My apologies to those with relatively slow computers, whatever the reason.
Mike,
I finally got out of that meeting at 3:30.
I'm not real sure of what you are asking me but, nonetheless, here goes:
(This is in the order of importance with 1 being the least.)
1. Don't bring a whole lot of mechanical parts. Too heavy and don't sell well. Do offer to carry heavy parts to the buyers vehicle or motel room. Bring your Radio Flyer. Sometimes they'll tip you. More profit!
2. Make sure mechanical parts are new or, if rare, in top shape. And, have some bags for the buyer to carry off his purchases in (people from Tennessee will rather have a tow sack, so bring a few of those along, also. Charge extra for them).
3. Make sure that any NOSR parts are in their box and identifiable by for what they fit. Tell folks that the NOSR stuff is even better than the original. It's not but they may be from Tennessee. You know.
4. Make sure any mechanical parts are NOS, if possible. They are worth a lot more. If they're in the original box, that is a big plus, too. The box may make good viewing in the buyers displace case at home. Note: Folk from Tennessee don't care about this display feature 'cause their curio cabinet is probably spelled "Kelvinator."
5. Bring no rusty parts unless it is a rare item. If you do bring rusty stuff, point out that the rust, no matter its amount or depth, is just "surface rust" and that it will clean up with just a little soap and water. Guarantee it or their money back. He'll be too embarrassed to bring it back. He

won't but she will. You know. So, beware.
6. Restorable accessories always sell well. Especially 1941 Fender Markers! If you're not sure about the years of an accessory, ask the potential buyer what year car they got. "Yep, that's it. Sir, you got a good eye and fantastic memory right there. Yesiree, you hit the nail right on the head. That there fender marker is sure 'nuff for a rare" light up" one for a 1938. It'll look real good and be very helpful in a-negotiating those hills back home in Tennessee. You can't be too careful seeing that that right front fender and tar don't get too close to those decorative white-painted tars and boulders folks place along edge of their property lines (note: It helps to speak their language. Try.)"
7. Be willing to haggle. My motto is to buy high and sell low. Yes, that's right.
Naw, just kidding. Anyway, name a price that is about twenty percent above what you'll be willing to take. That way you can look like the buyer has "stolen" it from you and then, after he has gone on, smile like a mule eatin briars.
8. Be prepared to make change. It is the vendors responsibility to make change, so have plenty of ones, fives, tens and twenties. Remember that folks attending the 100th anniversary meet will have sold an heirloom or two (or, if from Tennessee, maybe a pig or some extra jars of "shine") and thus are well heeled. They won't have anything less than a hundred dollar bill. Count on it.
9. Don't ever say to a potential customer, "I got more than that in it!" It makes absolutely no difference to the potential buyer what you have in it. Sounds ridiculous. Stick to your guns and let him walk off. Let him get a good way on down the lane. It may be a bluff, you see. If he doesn't turn back, then run after him with the part and say, "you know, I believe I'll take your offer after all. I need to lighten the load anyway." Works every time. And the "lighten the load" bit saves you face.
10. Neat accessories sell well. All except 1938 stuff. The dealers couldn't give that stuff away and so, unlike 1941 accessories, there is plenty of them out there. Leave 'um home. 1938 drivers tend to be real tight fisted anyway. Some of them even drive bottom-of-the-line business coupes. Imagine that!
11. Most important, don't even bother getting up out of your lawn chair if a fellow comes by with his wife

and he looks like he has to ask permission to ask the price of something. The sale just ani't a-gonna happen. Trust me. (I'm not dissin women folk here but just an observation gained over 40 plus years of vending. Women folk tend to be much more sane and cost conscious than men folk. Especially when it comes to old car accessories. When we spot a rare accessory, they sense us a-salivating like Pavlov's dog upon hearing a bell ring and that our brains (like Elvis) have "left the building" Yep!) They try to steer back into reality. Do too!
Hope this helps and good luck.
Charlie
BTW: In the "Parts For Sale" forum DIZ gave you some sound advice. You should take it.
BTW2: I got most of what I know from watching DIZ operate over the years. Grin.
BTW3: The above stuff was tongue in cheek. Please take no offense. DIZ and I have always been fair vendors. I'm sure Mike will be also.
I have never had but one part brought to me. It was in the late 70s and at Hershey. It was a NOS "in the box" accessory hood ornament. It was the one with a blue glass in the top. I think for 1946. Guy brought it back and told me that someone had told him that it was a Pontiac hood ornament. I gave the guy his money back right away and with no problem. I soon sold it to someone else. Soon after that the first fellow came back and said he had found out it was indeed the right hood ornament. I told him it was gone. He couldn't believe it. He was right disappointed. Yep. Was too.