I can tell you exactly what the likes of Rigby and LPL do, they talk to airlines. To be more specific they don't just talk to airlines, they present well-researched business cases with facts that can be backed up. They tell you what businesses are travelling and where to and how often and sometimes even what they are currently paying to go via points a/b/c. Then they offer you a good proposition to help with the start-up phase of operations. It's a fairly well-worn, successful formula but it needs a substantial amount of focussed legwork by the airport.