For the third time I've been contacted by someone who wants to buy an ad on one of my blogs. We've negotiated the content, terms and price, and for the third time I've gotten to putting the ad up and sending an invoice, usually with very rapid turnaround between emails. Then all goes silent on the buyer's side. Am I doing this wrong - should I be demanding payment before the ad is placed? Or is there just a certain number of folks out there who can't pull the trigger when buying advertising? What is a reasonable amount of time to leave an ad up while awaiting payment? Many thanks for your insight! Steve