There are three quite distinct thoughts in this verse.
First Put on your new nature,
When you became a Christian, repenting of sin and committing your life to following Jesus, you were given new life and a new nature as a child of God. So the instruction is to put this new nature on. Don’t just leave it behind in a cupboard like a winter coat for whenever you might need it. There is a conscious decision to be made daily to put on this splendid garment that enables us to please God. It is not just a once-for-all choice but something that we have to engage with every new day.
Then, be renewed as you learn to know your Creator
This is a process of discovery, learning something about the character and nature of God as revealed in the life of Jesus. Jesus is the perfect example of a life lived in harmony with God. There are those who ask themselves in every fresh situation ’What would Jesus do?’ That renews our commitment to believing and following Him.
And finally become like him.
That is the ambition and goal towards which we are moving. We shall never reach it fully in this life, but John reminds us ‘Dear friends, we are already God’s children, but he has not yet shown us what we will be like when Christ appears. But we do know that we will be like him, for we will see him as he really is. ‘ (1 John 3:2)
This whole process of putting on our new nature, discovering more of the character of God, and becoming like Him in daily experience is the pathway to practical Holiness.