How to know the will of God

John 7:17 (NKJV)

If anyone wills to do His will, he shall know concerning the doctrine, whether it is from God or whether I speak on My own authority.

Do you want to know the will of God? First of all, realize it only comes by revelation, specifically, in God's word. Secondly, realize that it is not until you are obedient to His word that it becomes self-evident as being truly His word. The verse above says: "Do His will, and you shall know about the doctrine." God will not reveal his truth until you are ready to respond to it. And when you respond to it, He will begin to reveal more truth.