Here are a few suggested websites that have good information on public speaking.
Here are a few suggested websites that present a large number of statistical studies to help bolster your arguments and presentations.
Asking these questions will help you to determine whether the resources you find are credible and reliable.
Who created the page? Does the person or organization have the appropriate credentials?
Why was this site created? What is the purpose of the site? For example, is it sponsored by a company that has a financial interest in the topic?
When was the page created and/or last updated? How current is the information?
Does the author cite trustworthy sources? How does the author support their argument?