John Gill Commentary 2 Chronicles 27:6

"So Jotham became mighty, because he ordered his ways before Jehovah his God." — 2 Chronicles 27:6 (ASV)

So Jotham became mighty
Having built towers and castles, and fortified cities, and conquered his enemies:

because he prepared his ways before the Lord his God ;
ordered, directed, and guided them according to the word and will of God, and walked as in the sight of God, having the fear of him continually before him.