Hear thou. The pronoun gives force and personality to the injunction (Job 33:33). Guide thine heart in the way. (For אשׁר, "to guide straight," see on Proverbs 4:14) "The way" is the right way, in distinction to the many wrong paths of life—the way of understanding, as it is called (Proverbs 9:6).
Septuagint, "Direct aright the thoughts of thy heart," for right thoughts lead to right actions.