Cultivate the habit of meditating on the word of God.
Keep this Book of the Law always on your lips; meditate on it day and night, so that you may be careful to do everything written in it. Then you will be prosperous and successful. Joshua 1:8
Whatever you constantly think about will influence what you do.
How do you want to act and speak? Work backwards by finding out the kind of thoughts and mindset that bring about a corresponding action and meditate on these.
Be not deceived: evil communications corrupt good manners.
34 Awake to righteousness, and sin not; for some have not the knowledge of God: I speak this to your shame. 1 Corinthians 15:33-34
Surround yourself with the right people. People who reflect and represent the kind of behaviour you want to see in your life. Not only can you learn from their ways, you can also draw support and grow by being around them. They facilitate an enabling environment.
And if you ever find yourself with people who think or behave contrary to how you want to think or behave going forward, either find a way to make known your stance, shield or extricate yourself from the situation if possible.
Finally, ask the Holy Spirit to be your helper. Commit yourself to the Holy Spirit on a daily basis and follow his lead.
But the Comforter, who is the Holy Ghost whom the Father will send in My name, He shall teach you all things and bring all things to your remembrance, whatsoever I have said unto you. John 14:26
In conclusion, be committed to renewing your thoughts. For habits to become a way of life, you need focus and commitment.