New and dynamic content is one of the best ways to repeatedly bring users back to your website. Stale or outdated information sets off an alarm that the site has not been receiving attention.
The Drupal modules of News, Events, and Blogs are ways to add frequently updated and dynamic content that can ripple onto different pages on your site. Try to add news, events and blog posts weekly, to have information of value and interest.
Another method of updating content on your site (that works automatically for you!) is to incorporate feeds, such as shared news from collaborative sites, or Twitter feeds from social media. A web feed lets websites continuously feed your site with notices of their new content. Content distributors syndicate a web feed, thereby allowing users to subscribe to it.