She is going to get married and live with her husband’s family, and she is asking for advice
Question

What advice can you offer a religiously-committed young woman who is about to get married to a man who is not religiously committed, except that he prays, but he does not always go to the mosque, but his reputation is good? She is going to live in her husband’s house with his family, his mother and siblings. This girl had no choice but to agree to this marriage because she is getting older and no religiously-committed young man has proposed marriage to her, who could help her to adhere to her religion. I hope that you can offer her some advice that will help her to remain steadfast in adhering to her religion in these difficult new circumstances, and that you will pray for her to remain steadfast and that she will be able to influence others and not be influenced by them.
Praise be to Allah.We advise this young woman to fear Allaah and remain obedient to Him and strive to please Him, and to help her husband to do good and become righteous. This is something that is possible, praise be to Allaah, but it needs wisdom and patience, and doing the things that lead to love and affection. 
She should make sure that the home is suitable for her, so that she will not be mixing with her husband’s brothers and relatives who are not her mahrams. The wife has the right to separate accommodation in which she can be at ease with her husband and she should not be forced to live with her husband’s parents or family. 
If she thinks that the house is suitable for her, then she should pray istikhaarah and ask Allaah for guidance, then she should go ahead and get married, and Allaah will decree good for her wherever it may be. 
We also advise her to strive to acquire knowledge and teach it, and to spread and revive the Sunnah, and to be the best person who comes to this house. She should remind them to pray and encourage them to do righteous deeds. She should bring them useful tapes and books, and be an example to them in her deeds and attitude. She should always ask Allaah for help, pay attention to her faith and commitment, take stock of herself, and look at her own deeds from time to time. She should know that people influence one another and that if a person does not influence others he will be influenced, so she should hasten to do good. 
We ask Allaah to help her and bless her with a righteous husband and good offspring. 
For information on istikhaarah prayer please see question no. 2217. 
And Allaah knows best.