READ THE ITEM DESCRIPTION THOROUGHLY.
A newbie to ebay recently bid for and won an item I was selling. Although not expensive it was a bulky item and the P&P was fairly high. The item was an a piece of IT equipment from an office clearance job lot which I bought. I did not have time to test the item concerned so I didn't know wether it worked or not, I put this information in the item description. However it soon became clear in a message from the customer that he hadn't read the description. He asked me if it worked! I didn't want to take advantage of his inexperience, so I told him I did not know if it worked & if he wanted to I would cancel the transaction, which he duly did. Leaving me out of pocket.
All this could and should have been avoided if he had read the description thoroughly.