It does not cost anything to send gifts to your neighbour and in return you can expect to receive free dishes back from them that you can then use to gain free money. Gifts ordered (most valuable first) are Stew, Grilled Chicken, Waffles, French Toast, Bacon and Eggs. A good strategy if possible is to send gifts like Stew or Grilled Chicken to ALL your neighbours once a day in one shot.
If you do not have much food left and do not want angry people leaving your restaurant you can always place A table or something in front of your door. Doing this though will also prevent people from entering your restaurant so you will not get any money.
Hi you can level up fast by making any dish cancel it and then make it again untill your in the level you want I did it and know I am in level 28 and I just started like 1 or 2 weeks agoo !!!! I hope it works the same way for you good luck!!!