Ask your husband for the issues that she may be touchy about. You may not know about family feuds and other such issues, so don't give your opinion before you know all the details. Also, get to know what she likes. If she loves saas-bahu serials then try and talk to her about it. It may be the ice-breaker that may lead to a great relationship with her.
Won't you love it if a guests comes to your house with a gift in his/her hand. Similarly, you mother-in-law will appreciate your love for her a great deal more if you take some gifts for her every now and then.
If you are out to impress, don't go dressed in clothes that are not ironed and hair that's not brushed properly. And skimpy clothes are a strict no-no. Similarly, it would do you good to not reveal the tattoo on your spine during your first meeting.
Accept the fact that a mother is bound to be possessive about her son. So, don't try and tell her how to cook for him. Even if your husband prefers your cooking to hers, don't point it out to her. Give her compliments about her culinary skills and even take recipes from her. A little flattery doesn't hurt, does it?
If you can't be overtly nice, then at least be polite. Don't overrule what she has to say. Also, don't get into an argument or debate with her during your first meeting.
To make sure that you communicate well with your mom-in-law call her at frequent intervals. Don't wait for her to call you. She will appreciate the fact that you keep in touch over the phone even when you can't be around.
Regardless of whether or not you plan to take it, take their advice. Your spouse's parents will be glad to feel that they still have some influence on their child's life.
Even if you have certain issues with your mom-in-law, don't wash the dirty linen in public. When you are attending a family event make sure that you don't pass snide remarks or discuss you differences in public.
Parents are obviously very possessive about their kids, and the best way to earn their respect is to treat their child well.
The most important thing is to not get too nervous, your mother-in-law is bound to be as nervous about meeting you. Secondly, learn to forgive and forget. This simple rule will make your life a lot easier.