You can boil, bake and fry your way around a kitchen standing on your head, blindfolded with your hands tied behind your back. Your menus are inventive and fresh, and there are no tough joints, soggy bottoms or burnt buns on your watch. In short you are cooking on gas (or Aga, if need be). But there’s more to be being a private chef than just being a culinary whizz kid. Here, we tell you how to improve on excellent…