(If you've asked questions in the comments, I answered in same days comment box)
When I examine my own mindset before marriage I realized I had a lot of expectations. I expected things to run in such a way, looks this way, act this way, think this way...etc.
Expectations can be as little as how you squeeze the toothpaste to who leads family devotionals.
You may expect things to operate like they did in your family.
This may sound silly, but this is one of those expectations I had in marriage: for John to check the locks at night before we went to bed. My dad always did a check of the house, every door was checked and every light was turned off. I just expected it to operate this way in my marriage.
When we got married, John didn't do the night time check of the house. It may me feel like he didn't care for my safety, which couldn't be farther from the truth. I expressed to him this silly expectation and he worked on making a point to check the house at night before bed.
Realistic expectations would be on my list of things to examine as you prepare for marriage. What can and should a marriage look like? What do you expect your marriage to look like? What things have your parents modeled that you expect in your marriage?
I believe that if you know what are your expectations of your mate before you enter in to marriage and if you are able to express these expectations to him or her, it provides a better spring board to that first year of adjustment in marriage.