How does a person making decisions know what is the will of God?
The will of God is not meant to be a secret we must uncover. God wants us to understand His will far more than we want to understand it. He always makes His will clear to those who seek it with an obedient heart.
Most of the real problem areas in the question of God's will are settled for us in Scripture. The Bible reveals that it is God's will for all of us to be:
(1 Timothy 2:3-4; 2 Peter 3:9)
(1 Thessalonians 4:3-7)
(1 Peter 2:13-15)
(Philippians 1:29; 2 Timothy 3:12)
If all those things are true in your life, you may do whatever you want. Psalm 37:4 says, "Delight yourself in the Lord; and He will give you the desires of your heart." That means that if you are conforming to God's will in all the five ways listed above, He will place in your heart desires that reflect His will. So do what you want to do!
For a more thorough explanation of this crucial topic, consider these resources: