The number 1 tip for those starting a business selling handmade products is to have your inventory & bookkeeping systems set up in advance.
During craft shows, you need to bring a craft show inventory sheet to take note of your sales. At busy craft shows, you might forget some stuff you have sold, so take the sheet below and use it as a guideline.
You can keep a simple inventory sheet. Just simply take a copy of it and take note when something sells, and when you get back home, update the online version of your spreadsheet or your inventory management software such as Craft Maker Pro.
If you click on the download link below, you should be able to view it in A4 format. As you sell various items, write a quick description and price on the page provided below. This makes the sale process way easier and more organized.
You might also be interested to download a complete printable craft show checklist.