How can you find out what is selling best online?

Answer 1

Research. I like to think about what I or my friends would want to buy online and then go see what it's going for on eBay and Amazon. There are also loads of blogs that will give you some tips, but most people will want money for their advice. @EbayCoach gives some ideas on twitter and she also has a website with some ideas.

EBay has an option on the left side of the screen that you can click on the "show only" and then check completed listings.

Here you can also look at the listings and see what made one product sell over another. I've notice that if you don't have buyer feedback its' a lot more difficult to get people to bid on your items.