my only advice is to make sure you are prepared. Make sure you know how much everything is, take a calculator and have a good float. You will get a few early birds trying to pick up the bargains too. When I did one a few years ago I had sold a good few items before my stand was even setup!!. Towards the end to get rid of the items I ended up reducing the prices as that way people thought they were getting a bargain. It may also be useful to take post-its/stick labels, in case people ask if they can pay for the item but leave it with you while they wonder round the rest of the sales. That way you know who things belongs to. Have Fun and Good luck xx