How to know what God wants you to do?

Not knowing what God wants you to do is a horrible place to be. Because the way of God leads to eternal life and the way outside him leads to death.
To not care or be ignorant is even worse. Bible says the way the seems right leads to destruction.

James 1:5-8
Living Bible

5 If you want to know what God wants you to do, ask him, and he will gladly tell you, for he is always ready to give a bountiful supply of wisdom to all who ask him; he will not resent it. 6 But when you ask him, be sure that you really expect him to tell you, for a doubtful mind will be as unsettled as a wave of the sea that is driven and tossed by the wind; 7-8 and every decision you then make will be uncertain, as you turn first this way and then that. If you don’t ask with faith, don’t expect the Lord to give you any solid answer.