Here's a seller's guide on how to maximise your profits at car boots, and minimise wasted effort.
1. Don't expect to just turn up and sell your stuff for a net profit. You must do your homework to make carbooting worth your while.
2. The two busiest carboot sales in North Norfolk are summer months only, at Aylsham (Saturdays) and Stalham (Sundays). Right off the A140 & the A149. They are run by the same gentleman (a character in himself), and will feature many of the same traders both days (if you make a double weekend of it).
3. Nominally sellers allowed on site from 9am for 11am opening to public. In reality, both sites sometimes close to more sellers by 8am, a lot of trading goes on between pitch-holders before 11am. Most people start packing up around 1:30pm. Both sites can have about 220 sellers and maybe 600 spaces for buyer's cars. Both are close enough to towns for foot traffic, too.
4. Turn up the week before you intend to sell (entry is free) and have a good stroll around as a buyer. Look at what sellers do that attracts you. Ask about prices and think to yourself "Would I pay that?". Make a mental note not to bring tonnes of stuff that is already on offer. If you can, stick around until the end and then ask sellers how much they made and what sold well. Most private sellers will tell you that they didn't sell much. Note how much and what kinds of stuff they are packing away back into their vehicles that didn't sell.
5. Postage and courier rates can be complicated, but the short answer is anything that you think is worth at least £3, especially if small or in very good condition will usually fetch much better prices in online auctions (eg., Ebid, Amazon, bonanza, Ebay, etc.). Expect most things to sell for 10p-£1. Where carboots are worthwhile is for bulky, very cheap or well-used stuff. And anything you want to shift fast & see the back of!
6. Anything you want to sell cheap, put a sign on it. You want to attract buyers to your stall & keep them there longer. I had loads of Beano magazines that no one looked at for 1.5 hours until I put out a "BEANO 10P EACH!" sign and 15 sold in the next half hour. I made a mistake by not putting up a similar sign "GIRL SCHOOL UNIFORM 50P EACH"; no one looked at those items at all.
7. Typical good sellers that won't fetch better on Ebay:
Ordinary buggies, kids garden toys, kids bikes, most car seats, men's work boots, any kind of fairly worn tool, generic Lego, toy tractors, professional football clothing, Quality children's shoes with signs of wear, wellies in any size, fancy dress with signs of wear, Hama bead items, anything heavy & awkward to post or with complicated-to-describe signs of wear, generic children's coats, heavy but worn items like tyres.
8. Will sell, but rather low prices and low volume of sales
Women's clothes well-displayed, Baby clothes, potty training & baby safety items, certain character toys (eg., Star Wars, Thomas the Tank Engine), pulp fiction.
9. Typical bad sellers (carboots are over-run with these):
Most clothes for age 3+, most books except collector items - better on Ebay, most children's toys (but see exception list above).
10. Sell on Ebay instead! Bundles of nice brand kid clothes if in excellent condition or BNWT. Nice condition expensive-to-buy-new toys in October-December.
11. Check your costs. It costs £9 to get my vehicle there and back, plus £7 pitch fee. All sellers start the day at a significant deficit. And most people who tell you how they made "£60!" won't be thinking to deduct that £16. I think I did well if I clear £10+ after costs on the day.
12. Make it clear you are open to haggling. When asked "What do you want?" hem and haw before giving your best hoped for price in a question mark voice. They'll counter-offer, you counter, a price is achieved. Hold your ground if you know you can expect the same or better on Ebay (again after costs, remember Ebay takes 20% typically, much more for low-value-high-postage items).
13. I've been told that Aylsham charity shops will turn away donations, they get so many from unsuccessful carbooters. Worth checking before you just turn up with all the stuff you couldn't shift.
14. Good tips about general carbooting principles. Some of that doesn't apply at Aylsham/Stalham (Vultures are kicked off site, for instance).