I have found it very helpful in my time here that to aviod MOST not all negitive feedbacks its best when a buyer buys from you to leave then feedback right then, .. its like praises them  for a job well done, their part is really over once they have paid.  If you make them as buyer feel like they must wait for you to give them feedback it sometimes backfires.  when  you bid on an auction on Ebay , you are entering into a  contract, your part of the contract if you are a buyer says you must pay forthe item if you win it. so you are finished once you pay.. the seller should then hold up their part by acknwlegeing to everyone that you do pay ontime and quickly. thats really the basis  of feedback.. you can always all things later to rebut or praise  the item.. I have found that it keeps my buyers most happy to see me  leave them feedback as sooon as they pay. just a helpful thought,. not even sure this is a guide.