We need to practice our speech as well. Loose and evil talk seems to be the norm in our culture, and it's easy for us to get caught up in it. But what would happen if, instead, we practiced saying nothing but "words that give grace to those who hear?" As disciples we must engage in the daily practice of disciplining our speech to reflect the building up of others rather than tearing down.
Next, Paul warns against grieving the Holy Spirit, which seems to be another way of saying we violate our baptism and our role in building up the community in holiness. If baptism is the mark of the Holy Spirit on us, then we need to be reminded daily that our conduct and thought life should reflect the Spirit's presence in our lives.
Our lives mirror the character of God
Paul sums up the argument by saying that if we're really practicing Christians, then things like bitterness, wrath, anger, arguments, slander and malice will eventually be "put away" and replaced with kindness, tenderheartedness and forgiveness. That will only happen through the discipline of practice.
The true gauge of success, according to Paul, is that character mirrors God in the way that a child mirrors a parent. The ultimate example of that kind of success is Jesus.