I've had a LONG run of possible buyers who exhibited every buying signal, knew my rates then dropped out just before the deal closed. Is it something in the air? It's never been like this before.
I use a prequalification questionnaire that covers access to budget (can they afford me); timeline (are they exploring or ready to hire) and more. It is pretty thorough and over the years has allowed me to score prospects. I don't mind those in the exploration phase because you need people in all phases of the sales pipeline to keep a steady flow. However, I do need to know how to invest my time. Even with your best efforts you will not close every deal, so don't be discouraged!