Tshirt tucked in tight with a light jacket or vest works. Just make sure the covering is semi-stiff. Hoodies does not work well. Sneakers for foot covering.
Pretty good summary above...in cold weather, the same principle applies using layers. If it's wet or cold, I wear whatever works best to stay warm and dry, and take the heavy outer layer off to shoot the stage. I like merino wool as a baselayer but underarmor works well too.