Πρέπει να προσέχεις να μην τον κάνεις θυμομένος.

English Translation

You must be careful not to make him angry.

This sentence has been changed on Tatoeba. First, the spelling θυμομένος is non-standard, with θυμωμένος the better form. And the better way to say ‘be careful not to make him angry’ is ‘ Πρέπει να προσέχεις να μην τον κάνεις να θυμώσει.’