Get a big foldable table that will fit in your car so you can set all your wares out on it. Make up a little float, plenty of change as people often have notes especially first thing in the morning. Take something to eat and drink as it can be a long morning especially if business is a bit slow. Take old carrier bags which means you get rid of them and the buyers can take their bargains away. Be prepared to bargain as people never want to pay the price you say you want
and last but not least, the most important thing! Don't let people open your boot for you and start routing in your stuff as we found out when we did our first carboot. We pulled up and my sister released the boot catch, big mistake. By the time we got out of the car there was about 5-6 people ferreting about in the bags
God knows if they nicked stuff as it was quite chaotic
Anyway, have a good time and enjoy it, we made about £100 after taking off the expenses and had a good laugh