Peer review has been the main form of appraisal of scientific knowledge for over a century. In essence, this process involves the evaluation of a scientific finding by independent experts prior to its dissemination to the scientific community, in an attempt to ensure that both the research and conclusions meet the necessary standards regarding quality, accuracy, relevance and novelty. However, although 'peer review' is considered the current gold standard, it is far from perfect. A focus on the methodology of an article and reviewers' training are key messages for the scientific community. Guidelines on how to review an article are needed and may help reviewers deal with this difficult process.