We become disciples of Jesus by spending time with him, through prayer and Bible study.
For discipleship, the gospels are especially valuable, because they remind us over and over of how startling, how amazing, this one we follow truly was and is.
So study Jesus’ words and deeds. Try to become like him in his character, his compassion, his integrity, his reliance on God, his careful rejection of human power and human structures.
The rest of the New Testament shows us how Jesus’ words and deeds were applied in different contexts by the Holy Spirit.
I am methodologically disposed to see the epistles and Revelation as extensions of the gospels and Acts. (And to see Acts as Luke intended it, “all that Jesus CONTINUED to do and teach,” the subtext of Acts 1.1.)
I do not see diversity in the New Testament on this point; you cannot set Paul against James, because they are both working out the application of the same Spirit and Lord to different situations.
And it’s wrongheaded to set Paul or James against Jesus, Church against Kingdom, etc. One testament, one covenant, one Kingdom, manifested in different circumstances and situations.