I've installed W3TC on my blog and used the Google speed test ( https://developers.google.com/speed/pagespeed/insights ) to checkout my site.
One of the major problems with my site was images that didn't have an expiry date. The exact message was "The following cacheable resources have a short freshness lifetime. Specify an expiry of at least one week in the future for the following resources:"
How can I use W3TC to set the expiry date on all of my static images such as the header logo, the footer logo, etc, etc. I do not use a CDN if that helps.