Hi TOL,
Been selling there for years. You asked so here is some tips.
You HAVE to choose a GENERAL CONDITION category. New, New Other, Seller Refurbished, Used, For Parts Or Not Working.
Many sellers are simply choosing USED for a used item. BUT YOU HAVE TO READ Ebay's DEFINITIONS of what these terms mean.
USED is defined as "....may show some signs of cosmetic wear but is fully operational and functions as intended....:
SO...this is essentially a GUARANTEE that your used item works 100% as should. IT DOESN'T MATTER if you put into your written description anything like "as is, no refunds, no returns etc..." THAT WON"T MEAN ANYTHING !! If the buyer finds a problem with your item and wants you to take it back THEN EBAY WILL MAKE YOU TAKE IT BACK AND ISSUE A FULL REFUND. You can always describe the item as working well and fully tested and stuff.
SO...if you absolutely do not want to take an item back for whatever your reasons, then you should list it as For Parts Or Not Working and then click on No Returns Accepted in the Shipping Details Section.
Be honest and provide lots of details in your ads. Think of any question a buyer might have and go ahead and provide those details up front.
If a buyer has a problem with your item and wants to send it back for a legitimate reason....just go ahead and take it back. In the end, no matter how a problem gets resolved, the buyer always holds the "power" to leave you a negative feedback and just a few of those can kill you....so it's best just to make your buyers happy and be pleasant about everything. You can always sell the item again and live another day.
If you have any kind of bad experience with a buyer then add them to your Blocked Bidders List so they can never buy from you again.
Ship your items quickly after the buyer pays. Like the same or next day.
Mail is cheapest. Get Delivery Confirmation on everything. It is your only proof that you sent the item. Get insurance on anything....say more than $50 in price. If the Post Office loses your box then you are screwed without it. You'll have to refund the money for "Item Not Received" and be out your money and the item.
I'm nearly at 700 transactions with a full half of them being sales and 100% positive rating. You CAN be very successful on Ebay and make a lot of money. I have, but you have to learn the game and follow the rules.....you'll do fine.
Good luck!