The Open Web Application Security Project (OWASP) is a worldwide not-for-profit charitable organization focused on improving the security of software. OWASP's mission is to make software security visible so that individuals and organizations are able to make informed decisions. OWASP’s is a community effort and its mission is to produce valuable information about appliation security to individuals, corporations, universities, government agencies and other organizations worldwide.
OWASP had published this year a major update to OWASP Top 10 2017 The Ten Most Critical Web Application Security Risks. I suggest you to read across the different sections of the document and evaluate if your aplications follow security OWASP guidelines.
Also the document include a valuable section named What´s Next for Developers and Organizations. I consider it important since mitigating security issues is a continued effort.
The important advise here is to wrap your mind around securing your web application and protect information against a number of different attacks.