All professional researchers are from time to time asked to carry out some reviewing. Although it is impossible from a practical point of view to achieve perfect reviewing, it is certainly mandatory for a responsible professional to try to do it in a good way. Good practices in peer-reviewing are of paramount importance for a proper operation of the research communities. In this paper an effort has been devoted to identify a series of criteria that can guide unexperienced reviewers to produce their first reviews in a way as objective and constructive as possible. Some parts of the paper are especially focused on the specific characteristics of engineering-related research areas. The paper discusses how important it is to have a constructive attitude, describes the main aspects to be analyzed when assessing the correctness and quality of a paper, discusses an important difference between the reviewing process of journal and conference papers, and finally makes some practical suggestions on the structure that a review report should have.