I always request the other party (buyer) leave me feedback after the sale. Ida e feedback first then send a mail/PM worded-
"I have left you positive (+1) itrader feedback. My feedback is very important I me, if you ar satisfied with the item & the transaction I would appreciate if you could leave me itrader feedback, to do this simply click the reply icon from the feedback I've already left for you, this was all the required info is already filled out for you, you simply type a comment and push submit".
That way they don't have to find the thread and find where to leave feedback, its simpler for them that way. They just type their comment, the rest is already done for them. I have gotten positive feedback from every sale I've made, I know doing it first so the other party can simply reply instead of having to do the work has helped me to get several ratings the other party wouldn't have taken the time to do on their own.
I really find it hard to comprehend why people arnt more inclined to leave feedback, the system works well and it can really help other members out. I always leave feedback at the earliest possible time.