You can design attractive visuals by following simple guidelines. One of these simple guidelines is the Rule of Thirds - a composition technique borrowed from photography and other visual arts that works wonderfully in PowerPoint.
Guideline 1.1 Text Alternatives: Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.
"This comprehensive collaborative learning workshop guide, developed from the ELI 2009 Fall Focus Session, contains a resource list and five workshop modules intended to reduce some of the extensive work involved in assembling the components and curriculum for such a program. Each of the modules contains topical guidelines, content, resources, and best practices, and each can be easily customized to fit the needs of your institution, department, or unit."