A: Ahlus Sunnah wal Jama'ah are in agreement upon eemaan increases with obedience and it decreases with disobedience.
Allaah says what is translated to mean:
As for those who believe, it has increased their Faith, and they rejoice. (At-Tawbah 9:124)In order for your eeman to increase, you have to increase in your worhip to Allaah subhanahu wa ta'aala. Actions, like the recitation of the Qur'aan and pondering over it's meaning, standing in the last part of the night prayer, fasting during the day, obedience to your husband, not using your tongue for disobedience will increase your eeman.
It is the removal of all of those things which are evil and purify yourself from those things that will increase your eeman. If a person wants to do a particular sin and their soul inclines towards that sin, if she leaves it off then this is a cause for your eeman to increase. If a person is commanded to do some type of worship and he does it seeking the face of Allaah, then that increases your eeman also.
The Rectification of the Muslim Women in the West with Q&A in London with Shaykh Maahir Al-Qahtaani (Hafidhahullaahu ta'aala) - 02/12/2011
Sisters Upon Al-Istiqaamah