The best way to know the will of God is to know God, to have a genuine relationship with your Father in heaven. The relationship between a Christian and God is like the relationship of a father and his child. A child that spends little time with their father will not know their fathers will, they will have difficulty relating with their father, and will not recognize his voice. In contrast, a child that has a deep loving relationship with their father will know what brings joy to their father, and what brings sadness. They will many times develop the same likes and dislikes as their father, and they will be able to distinguish their fathers face and voice from those of others.

This is the relationship God desires to share with us, one of love and compassion. He wants us to seek his will, to love what He loves, to hate what He hates. He wants us to listen for, and recognize His voice.

Like any relationship, this takes work. The more time and energy we devote to developing a deep and meaningful relationship with our God the more we understand. We do this by spending time with him daily in His Word, and in prayer. By putting our lives completely in His hands and seeking His will first in all we do.

Matthew 7:7-8 says Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you.  8 "For everyone who asks receives, and he who seeks finds, and to him who knocks it will be opened.

James 1:5 Says But if any of you lacks wisdom, let him ask of God, who gives to all generously and without reproach, and it will be given to him.

Seek the will of God, in His word, in prayer. As your relationship with God grows it will become more and more clear what the will of God is. As you spend time with God you it will become easier to distinguish between His voice and those of your flesh or other worldly influences.

It is important to remember that God will never contradict Himself. He will never tell you to do something that goes against His Word, or His character. The Bible is the best test to use to determine if something is from the Lord or is God’s will. Ask yourself;

Does it contradict the Word, and the teachings of Jesus?

Does it go against God’s character?

Will it glorify the Lord, or will it bring reproach upon the name of Christ?

Does it have the appearance of evil?

Lastly, seek Godly counsel. It is important to seek the counsel of brothers and sisters in Christ.
Proverbs 12:15 puts it this way

The way of a fool is right in his own eyes,

But a wise man is he who listens to counsel.