I am just... terrible at these types of games. Just getting through the tutorial portion I made two customers angry with me! "Yes, hello! We have hotdogs in white buns. No, we will not be offering whole wheat, non-gluten, vegetable alternatives, onions, chips or any of that stuff! You may have ketchup and/or mustard and, maybe relish. Good day, sir!"
One problem I had was that sometimes I'd get stuck holding a tray and it would be very difficult to put it down. All the other problems come from my lack of ability. :D