Praying the will of God

Jesus instructs us to pray that God's "will be done on earth as it is in heaven." And in dark Gethsamane he modeled that sort of prayer: "Not my will, but yours..."

I want to pray for God's will, but it's difficult. I often am unclear on what his will is. Do I pray for healing or comfort while dying? When a brother wonders off in disobedience, do I ask that God would spare them harm, or do whatever it takes? Other clear examples escape me. But I found the following prayer by Thomas Merton to be helpful:

My LORD God, I have no idea where I am going. I do not see the road ahead of me. I cannot know for certain where it will end. Nor do I really know myself, and the fact that I think that I am following your will does not mean that I am actually doing so. But I believe that the desire to please you does in fact please you. And I hope I have that desire in all that I am doing. I hope that I will never do anything apart from that desire. And I know that if I do this you will lead me by the right road though I may know nothing about it. Therefore will I trust you always though I may seem to be lost and in the shadow of death. I will not fear, for you are ever with me, and you will never leave me to face my perils alone. (found in "Thoughts in Solitude")