Express a personal rule or habit; 'I make it a rule to', 'I always make sure to'.
Long explanation:
The ~ことにしている grammar point is used to express a personal rule, habit, or decision that the speaker has made for themselves. It can be translated as 'I make it a rule to' or 'I always make sure to' in English. This grammar point is formed by attaching ことにしている to the casual form of a verb.