1.) Know that when you marry a person you marry their background, families, current situation, finances, health and a host of other things.
2.) Your in-laws are closely related to your spouse. They are his/her parents or guardians.
3.) The Bible admonishes the spouse to honor his/her parents or parent figures. Regardless of temperament, tribe, nationality etc.
Honour thy father and mother; (which is the first commandment with promise;) That it may be well with thee, and thou mayest live long on the earth.
4.) Your in-laws are like adopted parents to you.
5.) You must believe God to love them unconditionally as it says in 1 Corinthians 13:4-8 even when you think they don’t like you.
6.) No spouse should make the home of his/her parents their real home. The Bible admonishes the couple to leave their native homes and cleave to each other.
7.) Try not to discriminate between parents as to care, upkeep, finances etc.
8.) Recognize the reality that not all sets of parents have the same needs, so do not try to make their needs identical. For example, one parent may need remittances but the other may need to be remembered only on birthdays.
9.) Do not complain about your spouse to your parents. They are likely to be biased against him/her. Let love cover the multitude of your partner’s faults and seek pastoral counsel when you need help. Read the best books on marriage counseling.
10.) Be yourself with your in-laws as long as it does not breed offense.