Not all mother-in-laws are as scarey as they say. The key is to convince her that you are suitable for her son/daughter. That you are capable of taking care of them and your future children, as well as your parents in law. If she sees that you are a good person, kind, caring, responsible and hard working then she will eventually come round. It's always good to bring some presents too to show that you care and that you have the financial means to buy good things. Make sure you learn some Chinese customs related to etiquette too and obviously learn the language!

Oh, and just don't show up with a mohawk, piercings, tattered clothes and a harley davidson.

work according to her wishes but be diplomatic, try to keep the husband's trust and believe and expressly truly and politely... on the other hand we shall respect elders and older... if they get old they are weak and they do need the support... the more you are respect and decent with them. the more its better for you... make understanding talk to eachother about every problem and anything happened... keep in touch we each other.......
chinese do like gifts alot so give little perks to mother-in-laws according to her taste can be good sign for better relationship. i guess

Buy her some presents everytime you go out for tourism or a trip out of town, Show your careness and respect to your husband. Say good words of your mother-in-law before her friends. Do not show your expenses.

Hitman?

The only way to please your chinese mother-in-law is by buying her a house.

I somehow agree with you nixoncutie and partially agree with juneyao too.

Chinese mother in law, specially the traditional ones, always will look up at you for something unusual compare to a Chinese boy such as

- Can you afford a house and will she get a room whether her other children abandons her or not?
- Can you surprise her with unique, peculiar gifts where as her other son in laws can't?
- Can you flatter her with your nice words, publicly or privately?
- This one is my favorite, " Will you be able to cover up her social security cost so when she hits 55-60, she could get some amount back through your savings?

For me, I always believe this," Do what's possible for you to make her happy and don't cross your principles to make her happy because you have to, make her happy because you want to and do it in your own way."

I partially agree with above suggestions.

Do you know when is her birthday? Her anniversary? Have a dinner with them once a while. Go shopping with her at her favorite big supermarket. Imagine what her friends see you at a supermarket with her, you create yourself a good impression. The rest is a piece of cake.

i just tell my mother in law just to shut the f up

Usually it is too difficult for a foreigner to handle chinese mother-in-law. But in fact if you are a foreigner who has a chinese mother-in-law now, you do not need to worry about how to handle. Because once your mother-in-law allows her daughter marry with you, she would do anything good for your marriage. What you need to do is pleased your wife.

My wife is from Hong Kong. The most important thing is to treat her daughter well and that will make her happy. If she makes you some unusual food for you then eat it. She made me some shark fin soup which I would never otherwise eat. The shark is dead and she bought it for me so I ate it. If I didn't eat it then someone else would eat it. So I ate it to please my mother in law.

My mother in law did not like me at first because I stopped her daughter from coming home to live i Hong Kong for good. But after I visited her with my daughter then it changed. Just before we were going to leave on a plane her mother and her sisters were all asking her when she was going to marry me in Chinese. Even though I didn't understand what they were saying I knew what they were talking about. Spend time with your wife's family and let them get to know you.

Treat her the way you want her to treat you.

Of course, in theory this should work just fine but be aware of the idiosyncrasies that is China. She may, among other things, just show up and clean your apartment (laundry included) without notice. It happens. You may deem this inappropriate or an invasion of privacy - doesn't matter what you think. You married the daughter and it's a package deal. I feel guilty when she does this but have learned to chip in where I see an opening. I sometimes  bend and do stuff that I'm not so crazy about but in the end it's worth it. Sure makes for a happy family environment when mama leaves.

Be a man and stand your ground. Don't put up with the nonsense and prove you can support the family financially and mentally

buy her a lolipop and it will keep her mouth shut 

Ignore her dear ! 

Don't made it too exaggerate. for most chinese mother-in-laws. you only need to show properly respect to her and treat her daughter/son real good.