Pamy as a valid point. PayPal can be a saviour for transactions, but when things go wrong!.
Describe the goods truthfully, but be realistic.
Good close-up photos go a long way.
Keep the postal delivery charges reasonable. Make sure that you do not run at a loss, its easily done. Check weight and size before quoting postal costs.Postal and delivery arrangements can result in non-bidders. Offer insurance at extra cost or obtain Certificate of Posting (foc).Post item as soon as possible. If there is or will be delay, state this to the possible buyer.
Try to respond to 'sensible' email requests. You may get the 'odd' email, be careful, especially with mobiles.
Think about a reserve price, it can be an advantage as well as a disadvantage for you or a possible buyer. Some people charge a large deliver charge to cover the cost of the item.
Everyone as to start somewhere, and feedbacks can help. Some with zero rating, who outbids other buyers need careful consideration.The same rule applies to 'new' sellers.