Plan your strategy to use Drupal at the best of its capability and performance. As Drupal is written in PHP it requires that a module is loaded when needed, therefore it is highly recommended to install a module only if it is really necessary. Decide in advance which modules to use in your project.
Integrate Drupal with other systems using the web services API module. They can be used for reading feeds, exchange data between complex systems which generally produce Jason or XML files.
Develop a Facebook application with the core Facebook Platform technologies: Social Plugins, Graph API and Platform Dialogs. Let your website interact with the Facebook social network: News Feed, Notifications, competitions and implemet any kind of viral marketing campaigns.