If you're on shared Hosting and/or don't have access to changing the php.ini, there's an .htaccess statement that you can use in your Drupal's settings.php file to increase the Maximum Execution Time, setting it from the default 30 seconds to 60 seconds should be plenty, but if that's not enough you can go to 120 or whatever you choose, although I wouldn't get too out of control with the high numbers.
example:

ini_set('max_execution_time', 60);