well, i hired mine when i was very heavily pregnant. at the time, i told her that her main jobs were the cooking and the cleaning but over time, this has evolved to include childcare.
i have always treated her the way i would want to be treated. i keep in mind that she is an adult, and actually about 6 years older than i am, so that it became unnecessary to introduce "curfews" etc. i just told her that the flat was small (we've moved since) and that so long as she didn't disturb us coming in and she was ready to work the next day, it was her day off to do as she wished.
for the cooking....
i thought it would be easier for her if i went through my cookbooks and highlighted things i thought looked interesting. she could then select what she wanted to cook/what we had ingredients for and manage a menu on her own. it is still a collaberation, but she does most of it. i took her shopping with me for a few months, so that she could see what i bought and what i looked for. back then, we lived in db and she did most of the day-to-day shops while i did the "big" ones. now, we live in sai kung and i do all of hte shopping, but she texts me the shopping list of what she needs. it seem to work for us.
childminding...
when i had my first, i didn't want anyone to touch him... including hubby... so it was hard to let her take over some of it. now, i have two and a business that i run, so i don't have as much time as i would like taking care of the kids.
i am very thankful that my kids have someone who loves them and cares for them as if they were her own. i am not jealous as i have excellent relationships with my kids. when i'm around, they want me and only me. there is no doubt in their minds who their mother is. my helper has watched how i discipline the kids and does a variation on the same theme. i use a naughty step, she uses a naughty corner etc.
household chores...
she knows what needs to be done. she has made her own schedule and she is the one that decides when things get done. there are times, when something extra comes up and i mention it to her...ie... i think it's time to clean the air-con filters...etc. she manages her time very well, most of the time.
pay...
she started on minimum. we gave bonuses when we thought she deserved them or when there was extra work.
second contract i increased her salary 10%. we continued to give bonuses.
about to sign 3rd contract. not sure what we will do, as we are in the process of hiring her husband to work for us, too.
other than that, you have to remember that no one is perfect and everyone has their own strong points.
good luck!