If you have decided to live with her mother in law, you become a member of the family. Please specify what you feel about her, respect her as an individual and as a person. Ask yourself whether you are ready to consider the mother of your husband as a member of his family. Then, determine the boundaries of each person they are different. The division of the house with another person who belongs to a different generation, and whose personality is completely different, represents a major test of patience and diplomacy. So accept the fact that you and your mother-in-law - totally different personalities. You should not rely on fate require a precise definition of the boundaries, expectations and potential issues. Talk to each other about how you see your marriage. Don't assume all in some way arise by itself.
In addition, remember that your family situation is, unfortunately, slightly lower than the mother-in-law, for some reason: she is the mother of your husband, the older woman and the lady of the house in which you came to live. So try to build a good relationship with her, and don't be afraid to take the first step towards better relations.
Before you move into a new home, talk to her husband and financial issues. You should have absolutely clear understanding about how the family manages the finances, who pays for what, what financial costs will be expected from you. The difference in age, tastes and needs, likely excludes the presence of the total budget, therefore, insist on strictly separated "the box office".