I have met dozens of clients since I started, and I still get nervous before I meet someone. It wont go away, thats just how it is when meeting strangers, especially when you have no clue what they look like...
But, me personally...I rarely show up to an appointment without having had atleast 1 good drink. Some people do drugs before an appointment, but I choose not to. Wine, liquor is a better option but just enough to feel relaxed and comfortable.