Remember the one condition of open licenses: You must provide attribution.
Ideal attribution for images should include Title + Author (linked to their profile when possible) + Source (linked to it in the title) + License (link to license deed). As example, these are the attributions for images included in this page:
Publish with tools that are non-proprietary and produce formats that are easy to:
PDF format is ideal for text OER. Other alternatives include open source word processing applications, odt format (the open version of .doc/.docx), or an HTML web page.
The goal of the Accessibility Toolkit - 2nd Edition is to provide resources for each content creator, instructional designer, educational technologist, librarian, administrator, and teaching assistant to create a truly open textbook—one that is free and accessible for all students.
The World Wide Web Consortium (W3C) is an international community that develops open standards to ensure the long-term growth of the Web. Web Accessibility Principles | Easy Checks | Tips for Designing for Web Accessibility