If there's one thing that stands out in my mind right now, that I would like to have done better with my mind, it is the art and practice of critical thinking. We actually do something of the sort all the time, as we sift through what we think is of value and what is of lesser or no value in what we hear and see, in the world.
Critical thinking wants to hear and understand, and then critiques everything. For us in Jesus this means evaluating everything in light of God's truth revealed to us in Jesus in accordance with Scripture. This is an ongoing task as we keep working on both our understanding of this revelation from God, as well as our understanding of the world in which we live. I am reminded of John R.W. Stott's fine and helpful book, Between Two Worlds.
I should add that we need to keep being informed and formed by good theology based on Scripture and on the understanding given to the Church. Scripture is our basis, but we need to read it, and seek to understand it along with tradition, or how the Spirit has helped the Church to understand it over the centuries. And with the view of ever reforming theologically on the basis of Scripture, avoiding both the full and uncritical acceptance of tradition, and the rejection of tradition. The entire Church is united together, even though we don't live that out on many levels here, so that we must take into account the tradition which has been passed down for generations, while continuing to work on clearer and more accurate ways of understanding the truth in Jesus. But as those within the one tradition of the one Church. Of course, again, tradition is not infallible, so that we ever have to apply critical thinking, yet to depart from it is to fall into the error of departing from a primary means and agent of how the Spirit reveals God's truth in Jesus to believers.
This is just a beginning and limited sketch on this. What from your perspective might you like to share on this?