Be clear about your expectations about what her responsibilities are at your house and lay down some rules about what she can and cannot do. It’s not fair to be angry with your ayi about something you haven’t first explained, because every family is different. Things that you might want to be clear to her may be the areas you expect her to be clean or careful, what areas would you rather she leave alone and when you expect Ayi to be at your home. The best way to start off is with a trial period so you both know what you are getting yourselves into.
Be Aware and Prepared
Coming from a different background, usually from a rural area, your Ayi probably has a different approach to things. For example if you are at home, she may open your door without knocking and you might feel a bit uncomfortable with that; just tell her before something awkward happens. If your Ayi cooks for you, you should also be aware that Ayis usually buy vegetables and meat from local markets. If her way of dealing the chores doesn't suit your standards of hygiene, bring her with you to your preferred supermarket and make sure she knows exactly what you want her to buy in future.
If your Ayi is happy working for you, she will not only do a great job, but also help you with occasional errands you might need help with. So treat her nicely, it will make both of you happy. For example, if she makes a mistake, tell her nicely instead of getting angry. Occasional gifts or a Chinese New Year bonus will also make her feel appreciated.