eBay has worked well for me to sell items. Here are several things I do to make my life easier:
1. No returns. Returns give buyers an easier out to send an item back if it doesn't meet their exact specifications. No returns put the onus on buyers to make sure they really want the item. On my side, I take thorough pictures and include a lot of details, including damage and answers to anticipated question, in the description.
2. No auction. Unless your item is a hot commodity, you will always lose more money this way. Instead, I only do "Buy It Now" or "Best Offer," this gives me more control.
3. Pre-package and weigh the item to get accurate information for shipping. If I don't have a scale, any of the normal shipping stores will do it for free.
4. Include the cost of packing materials into the shipping costs.
5. No free shipping. I set the shipping price based on information from the previous two points.
6. No international shipping. This is always a pain in the ass.
7. I don't buy eBay's shipping label. I use third-party sites that offer cheaper rates. If eBay's is cheaper, then I buy their label.
8. Always communicate with buyers. If I can't ship an item immediately or some other issue arises that may delay the buyer from receiving the item, I let them know; usually they are fine with the delay and appreciative of the communication.
9. Don't use PayPal. eBay already cuts into my profit, and I don't need another company getting their cut just for being a middle man way. Thankfully, eBay allows for direct deposit for sales.
10. Feedback is everything. If a buyer doesn't leave feedback immediately after a sale, I follow up with a friendly reminder. I do that two more times and stop if they don't respond.