Techniques of constructive criticism aim to improve the behavior or the behavioral results of a person, while consciously avoiding personal attacks and blaming. This kind of criticism is carefully framed in language acceptable to the target person, often acknowledging that the critics themselves could be wrong. Insulting language and hostile language are avoided, and phrases are used like "I feel..." and "It's my understanding that..." and so on. Constructive critics try to stand in the shoes of the person criticized, and consider what things would look like from their perspective. 
Of all the Causes which conspire to blind
Man's erring Judgment, and misguide the Mind,
What the weak Head with strongest Byass rules,
Is Pride, the never-failing Vice of Fools.
Whatever Nature has in Worth deny'd,
She gives in large Recruits of needful Pride;
For as in Bodies, thus in Souls, we find
What wants in Blood and Spirits, swell'd with Wind;
Pride, where Wit fails, steps in to our Defence,
And fills up all the mighty Void of Sense!
If once right Reason drives that Cloud away,
Truth breaks upon us with resistless Day;
Trust not your self; but your Defects to know,
Make use of ev'ry Friend--and ev'ry Foe.