Which of the 4 "Do nots" listed at the beginning do you find most people struggle with?
Personally, what I have found is the tendency for people to read the New Testament while discounting the Old Testament. We are an incredibly evangelist church - with the motto to help people discover and love who Jesus is - sometimes it's easy to spend an incredibly amount of time in the New Testament without explaining the culture, context, and importance of the Old Testament. Additionally, I think it's easier as people to preach the grace and love of Jesus - while not knowing how to handle the some of the tougher concepts that exist in the Old Testament - even questions of some of the commandments and law wrote down. Even understanding the statement "the old law doesn't apply to us" - causes people to discount the Old Testament in entirety.
How does putting Christ as the center of the 2 Testaments change the way you interpret the Bible?
Understanding that Christ came as a response to all the ways that God tried to be united, reconciled, and lived amongst the jewish people is incredibly important to interpretation. Reading through the Old Testament you can see the heart of God for His people but the continued attempts and failures of humanity that spurred the need for Jesus. I don't see it as an ancient text but rather a text that while focuses on the Jewish people - I can consistently relate to in my own faults, failings, and even the desire I had to seek God myself, and understanding that the inkling that this wasn't the way it was supposed to be- and the why behind it.