Effective criticism is appropriately motivated and positively intended.
Effective criticism should be objective.
Effective criticism is specific, relevant, and to the point.
Effective criticism must be constructive, with the goal of improving a situation.
The most basic "rule-of-thumb" of effective criticism is: "Respect the individual, focus the criticism on the behavior that needs changing - on what people actually do or actually say." Ideally, effective criticism should be: positively intended, specific, objective, and constructive.
Knowing how to effectively criticize is a skill you will use throughout your life. Being able to give good criticism gives you the opportunity to be positively influential both personally and professionally. Effective criticism is useful for the following two reasons: (1) New ideas and perspectives will be discovered, and (2) Argument logic is tested, possibly revealing shortcomings.
The goal of constructive criticism is 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 and hostile language is avoided, and phrases used are like "I feel..." and "It's my understanding that..." and so on. Constructive critics try to stand in the shoes of the person being criticized, and consider what things would look like from their perspective.
Effective criticism should be:
As the name suggests, the consistent and central notion is that the criticism must have the aim of constructing, scaffolding, or improving a situation, a goal that is usually subverted by the use of hostile language or personal attacks.
Effective criticism can change what people think and do; thus, criticism is the birthplace of change. Effective criticism can also be liberating. It can fight ideas that keep people down with ideas that unlock new opportunities, while consciously avoiding personal attacks and blaming.
Source: Source: Boundless. "Giving Effective Criticism: Be Positive, Specific, Objective, and Constructive." Boundless Communications Boundless, 3 Mar. 2017. Retrieved 28 Jun. 2017 from https://www.boundless.com/communications/textbooks/boundless-communications-textbook/learning-to-listen-and-helping-others-do-the-same-5/giving-and-receiving-criticism-34/giving-effective-criticism-be-positive-specific-objective-and-constructive-151-10645/
carefully considered and meant to be helpful