# to reveal his Son in me

Possible meanings are 1) "to allow me to know his Son" or 2) "to show the world through me that Jesus is God's Son."

# his Son

This refers to the Son of God. It is best to translate "Son" with the same word that your language uses to refer to a human son.

# so that I might preach him

"so that I might preach about him" or "so that I might proclaim the good news about God's Son"

# I did not immediately consult with flesh and blood

"I did not immediately ask people to help me understand the message"