What new way of thinking or acting must you practice if you are to be like God?

A Christian is a 'footstep follower of Jesus' and The Bible actually tells them to 'be made NEW in the force actuating their minds". To be approved by God, Christians must 'stop walking in ignorance, learn what God wants and put on the 'new personality' which has been created according to God's will in righteousness. (Ephesians 4:17-24) In order to act 'according to God's will', we have to know what God's will is.
This takes a desire to please God and make the effort to learn what he expects. Everything we need to know is in the Bible.
The Bible gives us much direction on how to 'think and act' to be pleasing to God, but the most important is found at John 13:34&35 where Jesus says :"I'm giving you a NEW commandment, that you LOVE one another. BY THIS all will know that you are my disciples, if you have LOVE amongst yourselves".
1 John 4:8 says that 'he who does NOT love, has not come to know God, because God is love."
1 John 4:19 tells us that 'WE love, because HE first loved us', so by loving our brothers we are following God's example.(1 John 4:20&21) (Ephesians 5:1&2).
LOVE is the identifying mark of true Christianity. Love for God, Love for people, Love for ourselves....in that order. Keeping in mind that LOVE is the primary requirement in Christianity, everything else falls in place and our behavior changes as we get to know more and more about God , learn to love Him and make application of his example in our lives.
All of 1 John 4 and Ephesians 5 give us some direction on how to 'think and act' along with Ephesians 4:31&32, which is especially pointed, but there is much more, all based on love.
God has alot of information to help us make positive changes in our lives and, in fact, taking in this knowledge can mean our everlasting life (John17:3)