We recommend to read the following resources before you assess the manuscripts.
http://publicationethics.org/resources/guidelines
http://www.degruyter.com/view/supplement/s15477355_Peer_Review_Guidelines_for_Reviewers.pdf
http://www.ease.org.uk/publications/ease-toolkit-authors/how-serve-effective-referee-peer-review-process
http://www.ncfr.org/jmf/jmf-reviewers/reviewer-guidelines
http://www.elsevier.com/reviewers/reviewer-guidelines