Do not leave negative feedback unless the other person has already left you feedback to avoid a tit-for-tat senario.
I left negative feedback for a seller who;
Didn't respond to 5 daily messages requesting reply.
Waited 7 days before writing honest feedback.
Two items didn't fit. Wrong model sent.
Description was for 5-7 days delivery, but took 17.
I paid immediately through Paypal. Only inquired for location of items after a 7 day wait.
Left one negative and a nutral. I received 2 negatives for being honest.