The following trick will help you if you don't have much time or you are not making food, or your ovens are full. To perform the glitch you have to put something in front of your Bakery's door like a cash register for example. When the door is blocked nobody can get in so they wont give your bakery a bad star rating. Doing this allows you to level up faster because you won't get bad ratings. When you have sorted out your bakery and are ready for more people put the item blocking the door back to it's place and re-open.