There are many "rules" which various Christians claim for each other, or for themselves. Many of them are man-made and are irrelevant to being a Christian. There are many commands in the Bible which were given to Israel which weren't given to Christians, though not all Christians agree on which ones. It is easy to get confused with all the different views, but keep these two "rules" foremost:
Love the Lord with your entire being, and
love your neighbour as yourself.
If and when you get married, there are few simple additions (simple, not necessarily easy!
), which hopefully will be covered in your vows. Bear in mind also that an unbalanced emphasis on "rules" usually leads to an unhealthy religious practice called "legalism", which is not Christianity but which is terribly common among Christians. Christianity is characterized by grace and mercy better than by rules.
When someone becomes a Christian, the Holy Spirit (God) actually comes to live inside. He changes the person from the inside-out, so that they want to be like Jesus, and do so out of love by the power of the Spirit. Rules are fine for showing where there are boundaries, but they are useless for restraining our bad behaviour or for making us good.
One major message of the Old Testament is that the rules (the "Law" as it is called) didn't make the Israelites any better than the people around them. It just pointed out how badly they failed. That is why Jesus came in the flesh and died on the cross; to open for us a way to God which does not depend on our following "rules".
We embark on that way by believing in Jesus and trusting that His death was in our place, so that we neither have to follow all those rules to get to God, nor do we have to pay the penalty for failing to do so. Our continuing walk with Jesus is dependent upon His power, and our part is to allow the Holy Spirit to change us so that we act and think the way He wants us to. His way is full of love for us, and not full of rules for us to follow.