The single biggest mistake people make in relationship building. They do not follow up. And they do not follow up because they do not do it the night of the dinner/event/drinks. Every time I go to an event, in the car, on the way home, I email every person I met that night that I want to progress a conversation with. 99% of people do not do this. They say, I will do it tomorrow and they never do. That said, at the end of an evening, in the back of an Uber, I do not want to type 10…