The peer reviewer is responsible for critically reading and evaluating a manuscript in their specialty field, and then providing respectful, constructive, and honest feedback to authors about their submission. It is appropriate for the Peer Reviewer to discuss the strengths and weaknesses of the article, ways to improve the strength and quality of the work, and evaluate the relevance and originality of the manuscript.

Before you accept or decline an invitation to review, consider the following questions:
• Does the article match your area of expertise? Only accept if you feel you can provide a high quality review.
• Do you have a potential conflict of interest? Disclose this to the editor when you respond.
• Do you have time? Reviewing can be a lot of work – before you commit, make sure you can meet the deadline.
Respond to the invitation as soon as you can – delay in your decision slows down the review process, whether you agree to review or not. If you decline the invitation, provide suggestions for alternative reviewers.

When reviewing the article, please keep the following in mind:
Content Quality and Originality,
Is the article sufficiently novel and interesting to warrant publication? Does it add to the canon of knowledge? Does the article adhere to the journal's standards? Is the research question an important one? In order to determine its originality and appropriateness for the journal, it might be helpful to think of the research in terms of what percentile it is in? Is it in the top 25% of papers in this field? You might wish to do a quick literature search using tools such as Scopus to see if there are any reviews of the area. If the research has been covered previously, pass on references of those works to the editor.
Organization and Clarity
Title: Does it clearly describe the article?
Abstract: Does it reflect the content of the article?
Introduction: Does it describe what the author hoped to achieve accurately, and clearly state the problem being investigated? Normally, the introduction should summarize relevant research to provide context, and explain what other authors' findings, if any, are being challenged or extended. It should describe the experiment, the hypothesis (es) and the general experimental design or method.
Method: Does the author accurately explain how the data was collected? Is the design suitable for answering the question posed? Is there sufficient information present for you to replicate the research? Does the article identify the procedures followed? Are these ordered in a meaningful way? If the methods are new, are they explained in detail? Was the sampling appropriate? Have the equipment and materials been adequately described? Does the article make it clear what type of data was recorded; has the author been precise in describing measurements?
Results: This is where the author/s should explain in words what he/she discovered in the research. It should be clearly laid out and in a logical sequence. You will need to consider if the appropriate analysis has been conducted. Are the statistics correct? If you are not comfortable with statistics, please advise the editor when you submit your report. Interpretation of results should not be included in this section.
Conclusion/Discussion: Are the claims in this section supported by the results, do they seem reasonable? Have the authors indicated how the results relate to expectations and to earlier research? Does the article support or contradict previous theories? Does the conclusion explain how the research has moved the body of scientific knowledge forward?
Tables, Figures, Images: Are they appropriate? Do they properly show the data? Are they easy to interpret and understand?
Scope - Is the article in line with the aims and scope of the journal?

Your review will help the editor decide whether or not to publish the article. Giving your overall opinion and general observations of the article is essential. Your comments should be courteous and constructive, and should not include any personal remarks or personal details including your name.
Providing insight into any deficiencies is important. You should explain and support your judgement so that both editors and authors are able to fully understand the reasoning behind your comments. You should indicate whether your comments are your own opinion or are reflected by the data.

Summarize the article in a short paragraph. This shows the editor you have read and understood the research.
Give your main impressions of the article, including whether it is novel and interesting, whether it has a sufficient impact and adds to the knowledge base.
Point out any journal-specific points – does it adhere to the journal’s standards?
If you suspect plagiarism, fraud or have other ethical concerns, raise your suspicions with the editor, providing as much detail as possible. Visit Elsevier’s Ethics site or the COPE Guidelines for more information.
Give specific comments and suggestions, including about layout and format, Title, Abstract, Introduction, Graphical Abstracts and/or Highlights, Method, statistical errors, Results, Conclusion/Discussion, language and References.

When you make a recommendation, it is worth considering the categories the editor most likely uses for classifying the article:
Reject (explain reason in report)
Accept without revision
Revise – either major or minor (explain the revision that is required, and indicate to the editor whether or not you would be happy to review the revised article)

The editor-in-chief ultimately decides whether to accept or reject the article. The editor will weigh all views and may call for a third opinion or ask the author for a revised paper before making a decision. The reviewers are informed about the final decision about the manuscript.