Keeping track of revenue

Hi everyone, I started doing Depop a month ago just by selling my old clothes. I made about $500 so far. I am aware that I need to pay taxes on that but I am also interested in reselling. I have a question how to keep track of my revenue and how much I paid/sold for. I don’t know how to do it in a way that my accountant won’t get confused. Should I print all my sold receipts or keep a balance sheet to keep track of the costs and earnings? Also what should I do about selling my old clothes? Technically, I bought them for personal use but sold them later. Thanks for help in advance.