I buy and sell on eBay. In no particular order:
1) I only sell things I know, so I can write an accurate and enticing description. Mostly it has been bicycle stuff, photography stuff, and computer stuff. When a friend asked me to sell baseball cards, I declined, because I know nothing about the market.
2) I get the packaging and know the weight and shipping cost BEFORE I create the auction. I use an inexpensive electronic kitchen scale. I will not buy anything without a stated shipping charge, and I assume other people dislike uncertainty as much I do.
3) Except for unusually heavy or bulky items, I ship free – the sales price includes shipping. I like the simplicity of one number, all-inclusive when I buy things. I assume other people do, too.
4) I almost always ship USPS Priority Mail. That’s for light items costing $50 or more. Cheaper stuff I ship regular mail. Big, bulky, and heavy items I figure out the best deal among UPS, USPS, and Fed Ex. For example I found Fed Ex to be the best deal (at the time) for shipping car doors and guitars.
5) To research the market, check “Sold Items” in the eBay search. Asking prices don’t mean much, you need to see actual past selling prices.
6) Now this is the fun/scary part – it takes confidence in your knowledge of the market – I start all auctions at $0.01 with no reserve. Yes, I could possibly sell a $900 camera or $1,000 guitar for one penny! But in dozens of auctions, I have only once been disappointed at the selling price. Almost every other time I get more than I would have asked for with a set price.
The price usually stays very, very low until the last few days of the auction, making it a nail-biter. But the ridiculous low prices attract attention and bidders.
7) Good pictures earn good prices. Take care with our setup, lighting, backgrounds, etc. Copy other sellers whose auctions would make YOU buy stuff.
8) Be honest about product downsides, wear and tear, flaws, etc. If there are stains or chips or rips, show them close-up in photos. It’s better to set expectations too low than too high.
9) Ask for feedback. A few days after delivery of the product, I send an email saying something like:
“Hi, jca2. I see the widget was delivered Monday. I hope you are enjoying it as much as I did. Let me know if there are any issues with delivery or condition
“I appreciate our business, and I entered positive feedback for you on eBay. If you feel inclined, please do the same for me with this link (insert link here). Thanks!”
Lots of people will not bother giving you feedback. Don’t worry about it.