Don't be a food Nazi
The biggest complaint helpers have about their employers is that they are stingy with food. In almost every case the complaint is against the wife who manages the food budget. I have heard scores of stories about Hong Kong employers who measure out the exact amount of rice to be used at each meal, and who get angry if the rice is used up too fast, and who even go so far as to blame the helper for being "greedy".
Almost everywhere I travel in Asia I find that people are extremely generous with food. Farmers in China earning 500 yuan a month will spend half of their monthly income to feed a foreign guest who is visiting. How has the culture that gave us "Sik Faan Mei?" ended up producing food misers or food nazis in Hong Kong? If you want to keep a good helper, then lighten up when it comes to food. Don't talk about it, gripe about how much money you spend on groceries, just bite your tongue and feed them well. Your helper will find a hundred ways to repay your kindness, and will do her best to save you money when shopping. Have an abundance mentality, be generous, bless your workers, and trust God to bless you in return.