Caching is one of the easier ways that you can improve the load times of your pages, and you may even save some bandwidth in the process.
Caching works by preventing additional requests for content that has already been downloaded. What you would typically do to prevent requests, is to set an expatriation date for certain static resources, and ensure that dynamically delivered resources are validated properly with the HTTP If-modified-since.
Dynamic content includes any content delivered trough a CMS, what you want to make sure, is that browsers correctly performs a conditional request for your page. If the content or CMS it self has been updated, then the server should respond with a 200 Ok code, and the content should be re-downloaded. If nothing changed, then the server should respond with a 304 Not Modified code, and the resource should be fetched from the browsers cache.