This chapter was a continuation of chapter 11, in developing your relationship with God. Having a sincere and strong relationship with anyone won't just happen, but it requires desire, time and energy.
--First off, you must be honest with God. Express how you feel, and what troubles you. Job was honest with God, and vented his feelings and troubles. In the end, God respected Job's honesty and blessed him. God is very honest with us in return. He does not try to cover things up, but God is straightforward. When He is fed up, He will let it be known, and when He is pleased, likewise. God also keeps all of his promises. God wants that same frank honesty with us. Confess hidden anger or resentment, because bitterness can hold back your sincere relationship with God.
--You must also obey God in faith. He says "You are my friends if you do what I command". We should obey God, not out of fear or obligation, but because we love him, and we desire to follow him. God especially treasures simple acts of obedience, and acts that may go unnoticed.
--Also, value what God values. Being on one accord of what God wants and likes to see will strengthen your relationship with Him
--Lastly, you must desire the friendship with God more than anything else. You'll have to put some things aside, and some people aside, but God loves when we crave him with passion.