The holidays provide a great time of the year for just about anyone to make money on Ebay. The easiest way to decide what to sell is to watch, right now, what the trends are. What are the hottest toys going to be this year? What was the most popular movie and what might sell in relation to that movie? You can find that info simply by watching TV or reading the newspapers or magazines.
Once you have determined what the hottest items will be, then watch your stores for discounts and coupons. Many times a popular item will sell out a month before Christmas. If you have that one of a kind item, your auction may go wild.
Two years ago I found the game Electronic Battleship in my local discount Ollies store. I purchased about 16 of those games. I could have kicked myself for not buying more. I paid $24 each for them and my average auction win came in at around $50. That's not a bad return on my investment.
If you find something of interest in your local discount store that you think will sell, write the name of the product down and the price and go to Ebay. Type in the name and see how many come up. That will show you if the product you want to sell is competitive. The next thing to do is to see if anyone is actually buying the product. To do that, look on the left hand side to find the words "completed listings". Make sure you are signed in to do this. Then put a check in the box and search again with the exact search term you searched before. That will show you how many of the items have actually sold (in green) and how much they went for. Then you can determine if the product is worth buying.