gistfile1.txt

<?php

/**
 * Implement hook_form_FORMID_alter().
 */
function MODULE_form_blog_node_form_alter(&$form, &$form_state) {

  // Change label of save button.
  $form['buttons']['submit']['#value'] = t('Post');

  // Disable preview button.
  $form['buttons']['preview']['#access'] = FALSE;
}