1) never pressure for feedback because no feedback is better than feedback from an agitated buyer saying you are a pest.
2) Always wait for buyer feedback first, I have seen one buyer who had received over 1000 and only posted 2 reds in return. Do not encourage them.
After selling over 1,000 items over 95% of my buyers have left me glowing feedback with only one negative, (can't please everyone

By the way as a buyer I always aim to leave feedback first.