It's easy to criticize someone but it's harder to criticize ourselves. Do we not see ourselves - our true selves or perhaps we are truly oblivious to who we really are and what we represent.
Before we begin to criticize another individual or pass judgement, we should look closely at ourselves. When we criticise another, often we are really seeing our weaknesses before our eyes. Once looking at ourselves, we should be able to analyse our weaknesses and work on them gradually.
Letting go of expectations is another reason why we shouldn't criticize individuals. We all have expectations about certain individuals, but they are not perfect and neither are we. Throughout our lives, people will disappoint us, but we have to remind ourselves of their good qualities. Leave the expectations to God. "My soul, wait silently for God alone, for my expectation is from Him" (Psalm 62:5)
Before the need to criticize, ask for guidance.